C++ primer 第五版 第二部分 部分习题答案

8.1

#include <cstdlib>    #include <iostream>  #include <string>using namespace std;istream &f(istream &i){string s;while(i>>s){cout<<s<<" ";}i.clear();return i;}int main(int argc, char *argv[])  {     f(cin);   system("PAUSE");       return 0;    } 

8.4

#include <cstdlib>    #include <iostream>  #include <fstream>#include <string>#include <vector>using namespace std;int main(int argc, char *argv[])  {  vector<string> ss;string temp;ifstream in("a.txt", ifstream::in);if(in){while(getline(in,temp)){ss.push_back(temp);}}in.close();for(auto s:ss){cout<<s<<endl;}   system("PAUSE");       return 0;    } 

8.5

#include <cstdlib>    #include <iostream>  #include <fstream>#include <string>#include <vector>using namespace std;int main(int argc, char *argv[])  {  vector<string> ss;string temp;ifstream in("a.txt", ifstream::in);if(in){while(in>>temp){ss.push_back(temp);}}in.close();for(auto s:ss){cout<<s<<endl;}   system("PAUSE");       return 0;    } 

8.9

#include <cstdlib>      #include <iostream>    #include <fstream>  #include <sstream>#include <string>  #include <vector>  using namespace std;    int main(int argc, char *argv[])    {        vector<string> ss;      string temp;      ifstream in("a.txt", ifstream::in);      if(in){          while(getline(in,temp)){  istringstream record(temp);cout<<record.str()<<endl;            ss.push_back(temp);          }      }  in.close();      /*for(auto s:ss){          cout<<s<<endl;      }*/     system("PAUSE");         return 0;      }   

8.10

#include <cstdlib>      #include <iostream>    #include <fstream>  #include <sstream>#include <string>  #include <vector>  using namespace std;    int main(int argc, char *argv[])    {        vector<string> ss;      string temp;      ifstream in("a.txt", ifstream::in);      if(in){          while(getline(in,temp)){              ss.push_back(temp);          }      }  in.close();      for(auto s:ss){  istringstream record(s);        while(record>>temp){cout<<temp<<endl;}    }     system("PAUSE");         return 0;      }   

8.13

#include <cstdlib>      #include <iostream>    #include <fstream>  #include <sstream>#include <string>  #include <vector>  using namespace std;    struct PersonInfo{string name;vector<string> phones;};bool valid(const string &s, string::size_type num = 10){return (s.size() == num);};string format(string s){return "["+s+"]";};int main(int argc, char *argv[])    {       string line, word;   vector<PersonInfo> people;   ifstream in("phone.txt");   if (in)   {   while (getline(in,line))   {   PersonInfo info;   istringstream record(line);   record>>word;   info.name = word;   while(record>>word)   {   info.phones.push_back(word);   }   people.push_back(info);   }   }   //check person info   for (const auto &entry:people)   {   ostringstream formatted, badNums;   for(const auto &num:entry.phones){   if(!valid(num)){   badNums<<" "<<num;   }else{   formatted<<" "<<format(num);   }   }   if(badNums.str().empty())   {   cout<< entry.name << " " << formatted.str() << endl;   }else{   cerr<< "input error: " << entry.name << " " <<" invalid number(s) " << badNums.str() << endl;   }   }   system("PAUSE");         return 0;      }   

9.2

#include <cstdlib>#include <iostream>#include <list>#include <deque>using namespace std;int main(int argc, char *argv[]){list<deque<int>> ls;system("PAUSE");return 0;}

9.4

#include <cstdlib>#include <iostream>#include <vector>using namespace std;bool findByIt(vector<int>::iterator &it1, vector<int>::iterator &it2, const int c){while (it1 != it2){if (*it1 == c){return true;}it1++;}return false;};int main(int argc, char *argv[]){vector<int> vec = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };cout << findByIt(vec.begin(), vec.end(), 8) << endl;//1cout << findByIt(vec.begin(), vec.end(), 12)<<endl;//0system("PAUSE");return 0;}

9.6

不支持“<”操作。

9.7

size_type

9.8

const_reference reference

9.13

#include <cstdlib>#include <iostream>#include <list>#include <vector>using namespace std;int main(int argc, char *argv[]){vector<int> vec = { 1, 2, 3, 4, 5 };vector<double> vec1(vec.begin(), vec.end());//list<int> ls = { 1, 2, 3, 4, 5 };//vector<double> vec1(ls.begin(), ls.end());for (auto i : vec1){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

9.14

#include <cstdlib>#include <iostream>#include <string>#include <list>#include <vector>using namespace std;int main(int argc, char *argv[]){list<char *> ls = {"what", "is", "your","name","?"};vector<string> vec1;vec1.assign(ls.begin(), ls.end());for (auto i:vec1){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

9.15

#include <cstdlib>#include <iostream>#include <vector>using namespace std;int main(int argc, char *argv[]){vector<int> vec1 = { 1, 2, 3, 4, 5 };//vector<int> vec2 = { 1, 2, 3, 4, 5 };vector<int> vec2 = { 1, 2, 3, 4};if (vec1 == vec2){cout << "vec1 == vec2";}else{cout << "vec1 != vec2";}cout << endl;system("PAUSE");return 0;}

9.16

#include <cstdlib>#include <iostream>#include <vector>#include <list>using namespace std;int main(int argc, char *argv[]){vector<int> vec1 = { 1, 2, 3, 4, 5 };list<int> ls1 = { 1, 2, 3, 4, 5 };list<int>::iterator itls = ls1.begin();vector<int>::iterator itvec = vec1.begin();//itls++;if (*itls == *itvec){cout << "元素相等";}else{cout << "元素不等";}cout << endl;system("PAUSE");return 0;}

9.17

元素类型必须支持“<”操作

9.18

#include <cstdlib>#include <iostream>#include <string>#include <deque>using namespace std;int main(int argc, char *argv[]){deque<string> de;string word;while (cin >> word){de.push_back(word);}deque<string>::iterator it1 = de.begin();deque<string>::iterator it2 = de.end();for (; it1 != it2; it1++){cout << *it1 << " ";}cout << endl;system("PAUSE");return 0;}

9.19

#include <cstdlib>#include <iostream>#include <string>#include <list>using namespace std;int main(int argc, char *argv[]){list<string> ls;string word;while (cin >> word){ls.push_back(word);}list<string>::iterator it1 = ls.begin();list<string>::iterator it2 = ls.end();for (; it1 != it2; it1++){cout << *it1 << " ";}cout << endl;system("PAUSE");return 0;}

9.20

#include <cstdlib>#include <iostream>#include <list>#include <deque>using namespace std;int main(int argc, char *argv[]){deque<int> deq1, deq2;deque<int>::iterator itd11 = deq1.begin();deque<int>::iterator itd21 = deq2.begin();list<int> ls;int num;while (cin >> num){ls.push_back(num);}for (auto i : ls){if (i % 2){itd11 = deq1.insert(itd11, i);}else{itd21 = deq2.insert(itd21, i);}}for (auto j : deq1){cout << "deq1:" << j << " ";}for (auto k : deq2){cout << "deq2:" << k << " ";}cout << endl;system("PAUSE");return 0;}

9.24

#include <cstdlib>#include <iostream>#include <vector>using namespace std;int main(int argc, char *argv[]){//vector<int> vec;vector<int> vec{1,2,3,4,5};cout<<vec.at(0)<<" "<<vec[0]<<" " << vec.front()<<" "<<(*vec.begin());cout << endl;system("PAUSE");return 0;}

9.25

#include <cstdlib>#include <iostream>#include <list>using namespace std;int main(int argc, char *argv[]){list<int> ls{1,2,3,4,5};//ls.erase(ls.begin(), ls.begin());//如果相等则不删除任何值//ls.erase(ls.end(), ls.end());////如果相等则不删除任何值ls.erase(++(ls.begin()), ls.end());//删除与范围相等个数的值for (auto i : ls){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

9.26

#include <cstdlib>#include <iostream>#include <list>#include <vector>using namespace std;int main(int argc, char *argv[]){int ia[] = { 0, 1, 1, 2, 3, 5, 8, 13, 21, 55, 89 };vector<int> vec(begin(ia), end(ia));list<int> ls(begin(ia), end(ia));vector<int>::iterator itvec = vec.begin();list<int>::iterator itls = ls.begin();while (itvec != vec.end()){if (!(*itvec % 2)){itvec = vec.erase(itvec);}else{itvec++;}}while (itls != ls.end()){if (*itls % 2){itls = ls.erase(itls);}else{itls++;}}for (auto i : vec){cout << i << " ";}cout << endl;for (auto i : ls){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

9.27

#include <cstdlib>#include <iostream>#include <forward_list>using namespace std;int main(int argc, char *argv[]){forward_list<int> flst = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };auto prev = flst.before_begin();auto curr = flst.begin();while (curr != flst.end()){if (*curr % 2){curr = flst.erase_after(prev);}else{prev = curr;++curr;}}for (auto i : flst){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

9.28

#include <cstdlib>#include <iostream>#include <forward_list>#include <string>using namespace std;void f(forward_list<string> &flst, const string str1, const string str2){auto prev = flst.before_begin();auto curr = flst.begin();bool isInList = false;while (curr != flst.end()){if (*curr == str1){curr = flst.insert_after(curr,str2);++curr;isInList = true;}else{prev = curr;if (++curr == flst.end()){if (!isInList){flst.insert_after(prev, str2);}}}}};int main(int argc, char *argv[]){forward_list<string> flst = {"what", "your", "name","this","name"};//f(flst, "name", "is");//what your name is this name isf(flst, "book", "is");//what your name this name isfor (auto i : flst){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

9.31

list 迭代器只实现了，++和--，操作符运算，因为是链表结构，所以insert之后它的迭代器仍然指向有效位置。所以没必为迭代器再次赋值。

而forward_list不能获得当前元素的前驱，所以不能用--运算符。

#include <cstdlib>#include <iostream>#include <list>#include <forward_list>using namespace std;int main(int argc, char *argv[]){list<int> lst = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };//forward_list<int> flst = { 0, 1, 2, 2, 4, 5, 6, 7, 8, 9 };forward_list<int> flst = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };auto itlst = lst.begin();auto itflst = flst.begin();auto prev = flst.before_begin();while (itlst != lst.end()){if (*itlst % 2){lst.insert(itlst, *itlst);itlst++;} else{itlst = lst.erase(itlst);}}while (itflst != flst.end()){if (*itflst % 2){itflst = flst.insert_after(itflst, *itflst);prev = itflst;itflst++;}else{itflst = flst.erase_after(prev);}}cout << "list:" << endl;for (auto i:lst){cout << i << " ";}cout<<endl <<"forward_list:" <<endl;for (auto i : flst){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

9.34

不正确，如果是奇数，则迭代器应该再加一次，才能指向被插入元素的下一个元素的位置。

9.41

#include <cstdlib>#include <iostream>#include <string>#include <vector>using namespace std;int main(int argc, char *argv[]){vector<char> v = { 'a', 'b', 'c', 'd', 'e' };string str(v.begin(), v.end());cout << endl;system("PAUSE");return 0;}

9.42

先预留100个字符空间。避免重新分配空间。

9.43 9.44

#include <cstdlib>#include <iostream>#include <string>using namespace std;void f(string &str, const string oldVal, const string newVale){cout << str << endl;//find oldValstring::size_type len = oldVal.size();string::size_type pos = 0;string temp;while (pos != str.size()){temp = str.substr(pos, len);if (temp == oldVal){/*str.erase(pos, len);str.insert(pos,newVale);*/str.replace(pos, len, newVale);}pos++;}cout << str << endl;};int main(int argc, char *argv[]){string s("now that is it has no is");f(s, "is","was");cout << endl;system("PAUSE");return 0;}

9,45

注意，迭代器版本的insert只能接受，字符的插入

#include <cstdlib>#include <iostream>#include <string>using namespace std;string f(string name,const string &pre,const string &aft){auto it = name.begin();name.insert(it, { pre[0],pre[1],pre[2] });name.append(aft);return name;};int main(int argc, char *argv[]){cout << f("marthin", "Mr.", "Jr.");cout << endl;system("PAUSE");return 0;}

9.46

#include <cstdlib>#include <iostream>#include <string>using namespace std;string f(string name,const string &pre,const string &aft){name.insert(0, pre);name.insert(name.size(), aft);return name;};int main(int argc, char *argv[]){cout << f("marthin", "Mr.", "Jr.");cout << endl;system("PAUSE");return 0;}

9.47

#include <cstdlib>#include <iostream>#include <string>using namespace std;int main(int argc, char *argv[]){string str = "ab2c3d7R4E6";string numbers = "23467";string chars = "abcdRE";string::size_type pos = 0;while ((pos = str.find_first_of(numbers, pos)) != string::npos){cout << str.at(pos) << " ";++pos;}cout << endl;pos = 0;while ((pos = str.find_first_of(chars, pos)) != string::npos){cout << str.at(pos) << " ";++pos;}cout << endl;pos = 0;while ((pos = str.find_first_not_of(chars, pos)) != string::npos){cout << str.at(pos) << " ";++pos;}cout << endl;pos = 0;while ((pos = str.find_first_not_of(numbers, pos)) != string::npos){cout << str.at(pos) << " ";++pos;}cout << endl;system("PAUSE");return 0;}

9.49

#include <cstdlib>#include <iostream>#include <fstream>#include <string>#include <vector>using namespace std;int main(int argc, char *argv[]){ifstream in;string temp, maxStr, ascender("bdfhiklt"), descender("gjpqy"), normal("acemnorsuvwxz");vector<string> vec;in.open("words.txt");if (in){while (in >> temp){vec.push_back(temp);}}for (auto str : vec){if (str.find_first_of(ascender) == string::npos && str.find_first_of(descender) == string::npos){cout << str << endl;if (str.size() > maxStr.size()){maxStr = str;}}}cout << maxStr << endl;system("PAUSE");return 0;}

9.50

#include <cstdlib>#include <iostream>#include <string>#include <vector>using namespace std;int main(int argc, char *argv[]){vector<string> vec = {"1","2","3","4","5","-6"};int sum = 0;for (string i:vec){sum += stoi(i);}cout << sum << endl;system("PAUSE");return 0;}

10.1 10.2

#include <cstdlib>#include <iostream>#include <algorithm>#include <vector>#include <string>using namespace std;int main(int argc, char *argv[]){//vector<int> vec;//int temp;vector<string> vec;string temp;while (cin >> temp){vec.push_back(temp);}//auto i = count(vec.begin(), vec.end(), 5);auto i = count(vec.begin(), vec.end(), "is");cout << i << endl;system("PAUSE");return 0;}

10.5

#include <cstdlib>#include <iostream>#include <algorithm>#include <numeric>#include <vector>using namespace std;int main(int argc, char *argv[]){char * roster1[] = { "hello" };char * roster2[] = { "hello" };cout << equal(begin(roster1),end(roster1),begin(roster2))<<endl;system("PAUSE");return 0;}

10.6

#include <cstdlib>#include <iostream>#include <vector>#include <numeric>#include <iterator>using namespace std;int main(int argc, char *argv[]){vector<int> vec;fill_n(back_inserter(vec), 10, 0);for (int i:vec){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

10.7

(1) 不正确，目的序列没有足够的元素个数。

(2)不正确，reserve只是分配了所需空间，但是并不改变元素个数，如果用resize就正确了。

10.9

#include <cstdlib>#include <iostream>#include <vector>#include <string>#include <numeric>#include <algorithm>using namespace std;void show(const vector<string> &vec){for (string i : vec){cout << i << " ";}cout << endl;}void elimDups(vector<string> &words){show(words);sort(words.begin(), words.end());show(words);auto end_unique = unique(words.begin(), words.end());show(words);words.erase(end_unique, words.end());show(words);}int main(int argc, char *argv[]){vector<string> vec;string temp;while (cin>>temp){vec.push_back(temp);}elimDups(vec);system("PAUSE");return 0;}

10.10

我认为不改变容器大小的原因是，某些改变容器大小的操作会使迭代器失效。

10.11

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <numeric>#include <algorithm>using namespace std;void show(const vector<string> &vec){for (string i : vec){cout << i << " ";}cout << endl;}bool isShorter(const string &s1, const string &s2){return s1.size() < s2.size();}void elimDups(vector<string> &words){show(words);sort(words.begin(), words.end());show(words);auto end_unique = unique(words.begin(), words.end());show(words);words.erase(end_unique, words.end());show(words);}int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in;in.open("10.txt");while (in>>temp){vec.push_back(temp);}elimDups(vec);stable_sort(vec.begin(), vec.end(),isShorter);show(vec);system("PAUSE");return 0;}

10.12

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <numeric>#include <algorithm>using namespace std;class Sales_data{public:Sales_data(const string s) :bookNo(s){}string isbn() const { return bookNo; }private:string bookNo;};void show(const vector<Sales_data> &vec){for (auto i : vec){cout << i.isbn() << " ";}cout << endl;}bool compareIsbn(const Sales_data &s1, const Sales_data &s2){bool b = s1.isbn() > s2.isbn();return b;}int main(int argc, char *argv[]){vector<Sales_data> vec = { Sales_data("123-445-667"),Sales_data("826-699-542"), Sales_data("454-336-728"),Sales_data("365-425-424") };show(vec);sort(vec.begin(), vec.end(), compareIsbn);show(vec);system("PAUSE");return 0;}

10.13

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;void show(const vector<string> &vec){for (auto i : vec){cout << i << " ";}cout << endl;}bool compare(const string &s){return s.size() >= 5;}int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in("10.txt");while (in>>temp){vec.push_back(temp);}show(vec);auto end_part = partition(vec.begin(),vec.end(), compare);show(vec);vec.erase(end_part, vec.end());show(vec);system("PAUSE");return 0;}

10.14

#include <cstdlib>#include <iostream>#include <vector>using namespace std;auto f = [](int a, int b)->int{return a + b; };int main(int argc, char *argv[]){cout << f(3, 4) << endl;system("PAUSE");return 0;}

10.15

#include <cstdlib>#include <iostream>using namespace std;int f(){int a = 0;auto f = [a](int b)->int{return a + b; };return f(3);}int f(int a){auto f = [a](int b)->int{return a + b; };return f(3);}int main(int argc, char *argv[]){cout << f() << endl;cout << f(3) << endl;system("PAUSE");return 0;}

10.16

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;void show(const vector<string> &v, string prefix = "", string suffix = "",string perPre = "", string perSuf = " "){cout << prefix;for_each(v.begin(), v.end(), [perPre, perSuf](string s){cout << perPre+s+perSuf ; });cout << suffix << endl;}void elimDups(vector<string> &v){show(v,"original: ");sort(v.begin(), v.end());show(v,"sort: ");auto end_uniq = unique(v.begin(), v.end());show(v, "unique: ");v.erase(end_uniq, v.end());show(v,"erase: ");}void biggies(vector<string> &v, const vector<string>::size_type sz){elimDups(v);stable_sort(v.begin(), v.end(), [](const string &a, const string &b){return a.size() < b.size(); });show(v, "stable_sort: ");auto fir_find = find_if(v.begin(), v.end(), [sz](const string &a){return a.size() >= sz; });for_each(fir_find, v.end(), [](const string &a){cout << a << " "; });cout << endl;}int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in("10.txt");while (in>>temp){vec.push_back(temp);}biggies(vec, 4);system("PAUSE");return 0;}

10.17

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;class Sales_data{public:Sales_data(const string s) :bookNo(s){}string isbn() const { return bookNo; }private:string bookNo;};void show(const vector<Sales_data> &vec){for (auto i : vec){cout << i.isbn() << " ";}cout << endl;}int main(int argc, char *argv[]){vector<Sales_data> vec = { Sales_data("123-445-667"),Sales_data("826-699-542"), Sales_data("454-336-728"),Sales_data("365-425-424") };show(vec);sort(vec.begin(), vec.end(), [](const Sales_data &a, const Sales_data &b){return a.isbn() > b.isbn(); });show(vec);system("PAUSE");return 0;}

10.18

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;void show(const vector<string> &v, string prefix = "", string suffix = "",string perPre = "", string perSuf = " "){cout << prefix;for_each(v.begin(), v.end(), [perPre, perSuf](string s){cout << perPre + s + perSuf; });cout << suffix << endl;}void elimDups(vector<string> &v){show(v, "original: ");sort(v.begin(), v.end());show(v, "sort: ");auto end_uniq = unique(v.begin(), v.end());show(v, "unique: ");v.erase(end_uniq, v.end());show(v, "erase: ");}void biggies(vector<string> &v, const vector<string>::size_type sz){elimDups(v);auto end_part = partition(v.begin(), v.end(), [sz](const string &a){return a.size() >= sz; });for_each(v.begin(), end_part, [](const string &a){cout << a << " "; });cout << endl;}int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in("10.txt");while (in >> temp){vec.push_back(temp);}biggies(vec, 5);system("PAUSE");return 0;}

10.19

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;void show(const vector<string> &v, string prefix = "", string suffix = "",string perPre = "", string perSuf = " "){cout << prefix;for_each(v.begin(), v.end(), [perPre, perSuf](string s){cout << perPre + s + perSuf; });cout << suffix << endl;}void elimDups(vector<string> &v){show(v, "original: ");sort(v.begin(), v.end());show(v, "sort: ");auto end_uniq = unique(v.begin(), v.end());show(v, "unique: ");v.erase(end_uniq, v.end());show(v, "erase: ");}void biggies(vector<string> &v, const vector<string>::size_type sz){elimDups(v);auto end_part = stable_partition(v.begin(), v.end(), [sz](const string &a){return a.size() >= sz; });for_each(v.begin(), end_part, [](const string &a){cout << a << " "; });cout << endl;}int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in("10.txt");while (in >> temp){vec.push_back(temp);}biggies(vec, 5);system("PAUSE");return 0;}

10.20

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in("10.txt");while (in>>temp){vec.push_back(temp);}cout << count_if(vec.begin(), vec.end(), [](const string &s){return s.size() >= 5; });cout << endl;system("PAUSE");return 0;}

10.21

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;void fun(){int i = 1;auto fc = [&i]()->bool{if(i > 0){--i;return true;}return false;};cout << fc() << endl;cout << fc() << endl;}int main(int argc, char *argv[]){fun();system("PAUSE");return 0;}

10.22

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>using namespace std;bool lengthUp(const string &s){return s.size() >= 5;}int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in("words.txt");while (in >> temp){vec.push_back(temp);}cout << count_if(vec.begin(), vec.end(), lengthUp);cout << endl;system("PAUSE");return 0;}

10.23
bind 的参数不限制

10.24

#include <cstdlib>#include <iostream>#include <vector>#include <string>#include <algorithm>#include <functional>using namespace std;bool check_size(const int &i, string::size_type sz){return i > sz;}int main(int argc, char *argv[]){string s = "world";vector<int> vec = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };auto find_first = find_if(vec.begin(), vec.end(), bind(check_size, placeholders::_1, s.size()));if (find_first != vec.end()){cout << *find_first << endl;}system("PAUSE");return 0;}

10.25

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>#include <functional>using namespace std;void show(const vector<string> &v, string prefix = "", string suffix = "",string perPre = "", string perSuf = " "){cout << prefix;for_each(v.begin(), v.end(), [perPre, perSuf](string s){cout << perPre + s + perSuf; });cout << suffix << endl;}bool check_size(const string &s, string::size_type sz){return s.size() >= sz;}void elimDups(vector<string> &v){show(v, "original: ");sort(v.begin(), v.end());show(v, "sort: ");auto end_uniq = unique(v.begin(), v.end());show(v, "unique: ");v.erase(end_uniq, v.end());show(v, "erase: ");}void biggies(vector<string> &v, const vector<string>::size_type sz){elimDups(v);auto end_part = partition(v.begin(), v.end(), bind(check_size,placeholders::_1,sz));for_each(v.begin(), end_part, [](const string &a){cout << a << " "; });cout << endl;}int main(int argc, char *argv[]){vector<string> vec;string temp;ifstream in("words.txt");while (in >> temp){vec.push_back(temp);}biggies(vec, 5);system("PAUSE");return 0;}

10.27

<pre name="code" class="cpp">#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <list>#include <string>#include <algorithm>#include <iterator>using namespace std;void show(vector<string> &v){for (auto s : v){cout << s << " ";}cout << endl;}void show(list<string> &l){for (auto s : l){cout << s << " ";}cout << endl;}int main(int argc, char *argv[]){vector<string> vec;list<string> ls;string temp;ifstream in("double.txt");while (in >> temp){vec.push_back(temp);}show(vec);sort(vec.begin(), vec.end());show(vec);unique_copy(vec.begin(), vec.end(), back_inserter(ls));show(ls);system("PAUSE");return 0;}

10.28

#include <cstdlib>#include <iostream>#include <vector>#include <list>#include <deque>#include <algorithm>#include <iterator>using namespace std;int main(int argc, char *argv[]){vector<int> vec = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };list<int> ls;vector<int> vec1;deque<int> dq;copy(vec.begin(), vec.end(), back_inserter(vec1));//1,2,3,4,5,6,7,8,9copy(vec.begin(), vec.end(), front_inserter(dq));//9,8,7,6,5,4,3,2,1copy(vec.begin(), vec.end(), inserter(ls,ls.begin()));//1,2,3,4,5,6,7,8.9cout << "vector: ";for (auto i:vec1){cout << i << " ";}cout << endl;cout << "deque: ";for (auto i : dq){cout << i << " ";}cout << endl;cout << "list: ";for (auto i : ls){cout << i << " ";}cout << endl;system("PAUSE");return 0;}

10.29

#include <cstdlib>#include <iostream>#include <fstream>#include <string>#include <vector>#include <iterator>using namespace std;int main(int argc, char *argv[]){ifstream file("10.txt");istream_iterator<string> in(file),eof;vector<string> vec(in,eof);for (auto s : vec){cout << s << " ";}cout << endl;system("PAUSE");return 0;}

10.30

#include <cstdlib>#include <iostream>#include <vector>#include <iterator>#include <algorithm>using namespace std;int main(int argc, char *argv[]){istream_iterator<int> in(cin),eof;ostream_iterator<int> out(cout," ");vector<int> vec(in,eof);sort(vec.begin(), vec.end());copy(vec.begin(), vec.end(), out); cout << endl;system("PAUSE");return 0;}

10.31

#include <cstdlib>#include <iostream>#include <vector>#include <iterator>#include <algorithm>using namespace std;int main(int argc, char *argv[]){istream_iterator<int> in(cin),eof;ostream_iterator<int> out(cout," ");vector<int> vec(in,eof);sort(vec.begin(), vec.end());unique_copy(vec.begin(),vec.end(),out); cout << endl;system("PAUSE");return 0;}

10.32

涉及到运算符重载，以后补更。

10.33

#include <cstdlib>#include <fstream>#include <iterator>#include <algorithm>#include <string>using namespace std;void f(string inName, string outName1, string outName2){ifstream in(inName);ofstream out1(outName1);ofstream out2(outName2);if (in){istream_iterator<int> itIn(in),eof;ostream_iterator<int> itOut1(out1," ");ostream_iterator<int> itOut2(out2," ");while (itIn != eof){if ((*itIn) % 2){*itOut1 = *itIn;}else{*itOut2 = *itIn;}++itIn;}}in.close();out1.close();out2.close();}int main(int argc, char *argv[]){f("int.txt","out1.txt","out2.txt");system("PAUSE");return 0;}

10.34

#include <cstdlib>#include <iostream>#include <iterator>#include <algorithm>#include <vector>using namespace std;int main(int argc, char *argv[]){vector<int> vec{ 1, 2, 3, 4, 5, 6, 7, 8, 9 };for_each(vec.crbegin(), vec.crend(), [](const int &i){cout << i << " "; });cout << endl;system("PAUSE");return 0;}

10.35

#include <cstdlib>#include <iostream>#include <iterator>#include <vector>using namespace std;int main(int argc, char *argv[]){vector<int> vec{ 1, 2, 3, 4, 5, 6, 7, 8, 9 };vector<int>::iterator itb = vec.begin();vector<int>::iterator ite = vec.end();while (ite != itb){--ite;cout << *ite << " ";}cout << endl;system("PAUSE");return 0;}

10.36

#include <cstdlib>#include <iostream>#include <iterator>#include <list>#include <algorithm>using namespace std;int main(int argc, char *argv[]){list<int> ls = { 1, 3, 0, 7, 9, 3, 2, 0, 0, 3, 1, 0, 4, 6 };auto zero_rit = find(ls.crbegin(), ls.crend(), 0);cout << endl;system("PAUSE");return 0;}

10.37

#include <cstdlib>#include <iostream>#include <iterator>#include <vector>#include <list>#include <algorithm>using namespace std;int main(int argc, char *argv[]){vector<int> vec{1,2,3,4,5,6,7,8,9,0};list<int> ls;auto l = vec.crbegin() + 3;auto r = vec.crend() - 3;copy(l,r,back_inserter(ls));for_each(ls.begin(), ls.end(), [](const int &i){cout<<i<<" "; });//7 6 5 4cout << endl;system("PAUSE");return 0;}

10.42

#include <cstdlib>#include <iostream>#include <iterator>#include <fstream>#include <list>#include <string>#include <algorithm>using namespace std;int main(int argc, char *argv[]){list<string> ls;ifstream in("10.txt");if (in){istream_iterator<string> itIn(in), eof;copy(itIn, eof, back_inserter(ls));ls.sort();ls.unique();for_each(ls.begin(), ls.end(), [](const string &s){cout<<s<<" "; });//fox jumps over quick red slow the turtle}in.close();cout << endl;system("PAUSE");return 0;}

11.4

#include <cstdlib>#include <iostream>#include <fstream>#include <map>#include <set>#include <string>#include <algorithm>  using namespace std;int main(int argc, char *argv[]){ifstream in("words.txt");//Age has reached the end of the beginning of a word age, has! reached, the; end. of, the, beginning! of. a Word. string temp;string::size_type pos = 0;map<string, size_t> word_count;set<char> include = { '.', ',', ';', '!' };while (in>>temp){transform(temp.begin(), temp.end(),temp.begin(),tolower);cout << temp << endl;for (auto &c:include){while ((pos = temp.find_first_of(c,pos)) != string::npos){temp.erase(pos,1);}pos = 0;}++word_count[temp];}/*a occurs 2 timesage occurs 2 timesbeginning occurs 2 timesend occurs 2 timeshas occurs 2 timesof occurs 4 timesreached occurs 2 timesthe occurs 4 timesword occurs 2 times*/for (const auto &w:word_count){cout << w.first << " occurs " << w.second << ((w.second > 1) ? " times" : " time") << endl;}cout << endl;system("PAUSE");return 0;}

11.7

#include <cstdlib>#include <iostream>#include <map>#include <vector>#include <string>#include <algorithm>  using namespace std;void addAccount(map<string, vector<string>> &m, const string key, const string name = ""){m[key].push_back(name);}int main(int argc, char *argv[]){map<string, vector<string>> account;addAccount(account,"A","a");addAccount(account, "A", "b");addAccount(account, "A", "c");addAccount(account, "b");for (auto &c : account){cout << c.first << " : ";for_each(c.second.begin(), c.second.end(), [](const string &s){cout << s << " "; });cout << endl;}cout << endl;system("PAUSE");return 0;}

11.12 11.13

#include <cstdlib>#include <iostream>#include <string>#include <algorithm>  #include <vector>#include <utility>using namespace std;int main(int argc, char *argv[]){//pair<string, int> p;vector<pair<string, int>> vec;string stemp;int itemp;while (cin>>stemp>>itemp){//p = make_pair(stemp, itemp);//pair<string, int> p = {stemp,itemp};pair<string, int> p(stemp,itemp);vec.push_back(p);}for_each(vec.begin(), vec.end(), [](const pair<string, int> &p){cout << p.first << " " << p.second << endl; });system("PAUSE");return 0;}

11.14

#include <cstdlib>#include <iostream>#include <map>#include <vector>#include <string>#include <algorithm>  #include <utility>using namespace std;void addAccount(map<string, vector<pair<string, string>>> &m, const string key, const string name = "", const string birthday = ""){m[key].push_back(make_pair(name,birthday));}int main(int argc, char *argv[]){map<string, vector<pair<string, string>>> account;addAccount(account, "A", "a","1999-9-9");addAccount(account, "A", "b","2000-1-1");addAccount(account, "A", "c","2014-9-9");addAccount(account, "b");for (auto &c : account){cout << c.first << " : ";for_each(c.second.begin(), c.second.end(), [](const pair<string, string> &s){cout << s.first << " " << s.second<<endl; });}cout << endl;system("PAUSE");return 0;}

11.17

#include <cstdlib>#include <iostream>#include <vector>#include <set>#include <string>#include <iterator>using namespace std;int main(int argc, char *argv[]){vector<string> v = {"hello","wow","are","you"};multiset<string> c;vector<string> v1;multiset<string> c1 = { "hello", "wow", "are", "you" };copy(v.begin(), v.end(), inserter(c, c.end()));//支持//copy(v.begin(), v.end(), back_inserter(c));//不支持，因为涉及到顺序问题//copy(c1.begin(),c1.end(),inserter(v1,v1.end()));//支持copy(c1.begin(), c1.end(), back_inserter(v1));//支持/*auto m = c.begin();while (m != c.end()){cout << *m << endl;++m;}*/auto m = v1.begin();while (m != v1.end()){cout << *m << endl;++m;}system("PAUSE");return 0;}

11.18 是 map<string, size_t>::const_iterator 类型

#include <cstdlib>#include <iostream>#include <map>#include <utility>#include <string>using namespace std;int main(int argc, char *argv[]){map<string, size_t> word_count = { {"hello",1} };map<string, size_t>::const_iterator map_it = word_count.cbegin();cout << map_it->first << endl;system("PAUSE");return 0;}

11.19

#include <cstdlib>#include <iostream>#include <set>#include <utility>#include <string>using namespace std;class Sales_data{public:Sales_data(const string s) :bookNo(s){}string isbn() const { return bookNo; }private:string bookNo;};bool compareIsbn(const Sales_data &lhs, const Sales_data &rhs){return lhs.isbn() < rhs.isbn();}int main(int argc, char *argv[]){Sales_data b("123-456-789");multiset<Sales_data, bool(*)(const Sales_data &, const Sales_data &)> bookstore({ b });multiset<Sales_data, bool(*)(const Sales_data &, const Sales_data &)>::const_iterator book_it = bookstore.cbegin();if (book_it != bookstore.cend()){Sales_data a(*book_it);cout << a.isbn() << endl;}system("PAUSE");return 0;}

11.20

#include <cstdlib>#include <iostream>#include <map>#include <utility>#include <string>using namespace std;int main(int argc, char *argv[]){map<string, size_t> word_count;string word;while (cin>>word){auto ret = word_count.insert({word,1});if (!ret.second){++(ret.first->second);}}for (auto &p : word_count){cout << p.first << " " << p.second << endl;}system("PAUSE");return 0;}

11.21

关键字word的size_t 数量加一。

11.24

插入一个 关键字 为 0 的元素， 并将它赋值为 1

11.25

会报错，因为没有分配空间

11.26

1、key_type 2、mapped_type

#include <cstdlib>#include <iostream>#include <map>using namespace std;int main(int argc, char *argv[]){map<string, int> m = { { "a", 0 }, { "b", 1 }, { "c", 2 } };map<string, int>::key_type a = "a";cout << m[a] << endl;cout << endl;system("PAUSE");return 0;}

11.28

#include <cstdlib>#include <iostream>#include <map>#include <vector>#include <algorithm>#include <string>using namespace std;int main(int argc, char *argv[]){map<string, vector<int>> m;vector<int> a = { 1, 2, 3};vector<int> b = { 4, 5, 6 };vector<int> c = { 7, 8, 9 };m["a"] = a;m["b"] = b;m["c"] = c;map<string,vector<int>>::iterator it = m.find("a");for_each(it->second.begin(), it->second.end(), [](const int &i){cout << i << " "; });cout << endl;system("PAUSE");return 0;}

11.30

pos.first 返回一个map迭代器，->second 标识查找关键字对应的内容

11.31 11.32

因为本来就是使用的有序容器，所以打印出来就是按字典排序的。

#include <cstdlib>#include <iostream>#include <map>#include <vector>#include <algorithm>#include <string>using namespace std;int main(int argc, char *argv[]){multimap<string, string> m = { { "jack", "bookC" }, { "jack", "bookB" }, { "james", "bookA" }, { "james", "bookB" }, { "zoe", "bookZ" }, { "zoe", "bookB" }, { "hair", "bookA" }, { "hair", "bookG" } };multimap<string,string>::iterator it = m.find("hair");if (it != m.end()){cout << "erase it" << endl;m.erase(it);}for (auto p : m){cout << p.first << " " << p.second << endl;}cout << endl;system("PAUSE");return 0;}

11.33

#include <cstdlib>#include <iostream>#include <fstream>#include <sstream>#include <map>#include <vector>#include <algorithm>#include <string>using namespace std;map<string, string> buildMap(ifstream &map_file){map<string, string> trans_map;string key;string value;while (map_file>>key && getline(map_file, value)){if (value.size() > 1){trans_map[key] = value.substr(1);}else{throw runtime_error("no rule for " + key);}}return trans_map;}const string & transform(const string &s, const map<string, string> &m){auto map_it = m.find(s);if (map_it != m.cend()){return map_it->second;}else{return s;}}void word_transform(ifstream &map_file, ifstream &input){auto trans_map = buildMap(map_file);for_each(trans_map.begin(), trans_map.end(), [](const pair<string, string> p){cout<<p.first<<"=="<<p.second<<endl; });string text;while (getline(input,text)){istringstream stream(text);string word;bool firstword = true;while (stream >> word){if (firstword){firstword = false;}else{cout << " ";}cout << transform(word, trans_map);}cout << endl;}}int main(int argc, char *argv[]){ifstream trans("trans.txt");ifstream input("needtrans.txt");word_transform(trans, input);cout << endl;system("PAUSE");return 0;}

11.34

会变成插入元素，这样转换的文本就没有起到作用。

11.35

程序依然正常运行。

11.36

它会抛出一个异常“no rule for”+key

11.38

改变类型即可。

12.1

它们共享数据

#include <cstdlib>#include <iostream>#include <vector>#include <string>#include <memory>using namespace std;class StrBlob{public:typedef vector<string>::size_type size_type;StrBlob();~StrBlob();StrBlob(initializer_list<string> il);size_type size() const { return data->size(); }bool empty() const { return data->empty(); }void push_back(const string &t){ data->push_back(t); }void pop_back();string& front();string& back();private:shared_ptr<vector<string>> data;void check(size_type i, const string &msg) const;};StrBlob::StrBlob() :data(make_shared<vector<string>>()){}StrBlob::~StrBlob(){}StrBlob::StrBlob(initializer_list<string> il) :data(make_shared<vector<string>>(il)){}void StrBlob::check(size_type i, const string &msg) const{if (i >= data->size()){throw out_of_range(msg);}}void StrBlob::pop_back(){check(0, "pop_back");data->pop_back();}string& StrBlob::front(){check(0, "front");return data->front();}string& StrBlob::back(){check(0, "back");return data->back();}int main(int argc, char *argv[]){StrBlob b1;{StrBlob b2 = { "a", "an", "the" };b1 = b2;cout << b1.size() << endl;//3cout << b2.size() << endl;//3b2.push_back("about");cout << b1.size() << endl;//4cout << b2.size() << endl;//4}cout << endl;system("PAUSE");return 0;}

12.2

#include <cstdlib>#include <iostream>#include <vector>#include <string>#include <memory>using namespace std;class StrBlob{public:typedef vector<string>::size_type size_type;StrBlob();~StrBlob();StrBlob(initializer_list<string> il);size_type size() const { return data->size(); }bool empty() const { return data->empty(); }void push_back(const string &t){ data->push_back(t); }void pop_back();string& front();const string& front() const;string& back();const string& back() const;private:shared_ptr<vector<string>> data;void check(size_type i, const string &msg) const;};StrBlob::StrBlob() :data(make_shared<vector<string>>()){}StrBlob::~StrBlob(){}StrBlob::StrBlob(initializer_list<string> il) :data(make_shared<vector<string>>(il)){}void StrBlob::check(size_type i, const string &msg) const{if (i >= data->size()){throw out_of_range(msg);}}void StrBlob::pop_back(){check(0, "pop_back");data->pop_back();}string& StrBlob::front(){check(0, "front");return data->front();}const string& StrBlob::front() const{check(0, "const front");return data->front();}string& StrBlob::back(){check(0, "back");return data->back();}const string& StrBlob::back() const{check(0, "const back");return data->back();}int main(int argc, char *argv[]){StrBlob b1;{StrBlob b2 = { "a", "an", "the" };b1 = b2;cout << b1.size() << endl;//3cout << b2.size() << endl;//3b2.push_back("about");cout << b1.size() << endl;//4cout << b2.size() << endl;//4cout << b1.front() << endl;//acout << b2.back() << endl;//about}cout << endl;system("PAUSE");return 0;}

12.3

不需要，因为它会改变vector。

12.4

因为size_type是一个无符号类型，赋值为-1它会越界，所产生的数值已经包含在了这个检测范围之中。

12.5

构造函数不能隐式转换，只能直接初始化或显式的使用构造函数。

12.6

#include <cstdlib>#include <iostream>#include <vector>#include <algorithm>using namespace std;void setVec(vector<int> *p){int temp = 0;while (cin>>temp){p->insert(p->begin(), temp);}}void showVec(vector<int> *p){for_each(p->begin(), p->end(), [](const int &i){cout<<i<<" "; });}int main(int argc, char *argv[]){vector<int> *p = new vector < int > ;setVec(p);showVec(p);delete p;p = nullptr;cout << endl;system("PAUSE");return 0;}

12.7

#include <cstdlib>#include <iostream>#include <vector>#include <algorithm>#include <memory>using namespace std;void setVec(shared_ptr<vector<int>> &p){cout << p.use_count() << endl;//1int temp = 0;/*while (cin>>temp){p->insert(p->begin(), temp);}*/}void showVec(shared_ptr<vector<int>> p){cout << p.use_count() << endl;//2for_each(p->begin(), p->end(), [](const int &i){cout<<i<<" "; });}int main(int argc, char *argv[]){shared_ptr<vector<int>> p = make_shared < vector<int> >(3,9);cout << p.use_count() << endl;//1setVec(p);cout << p.use_count() << endl;//1showVec(p);cout << p.use_count() << endl;//1cout << endl;system("PAUSE");return 0;}

12.8

有错误，因为返回的是布尔值类型，只能是0，1这样指针所指向的内存永远无法释放。

12.9

1、会导致r所指向的内存无法释放。

2、用 share_ptr 则不会存在此问题。因为当赋值时，它会减1 r的引用计数，然后增加q的引用计数。

12.10

正确，在处理函数中有2个引用计数，结束时不会被释放掉。

12.11

会被释放掉p所指向的内存

12.12

a.合法，拷贝sp增加引用计数  b.不正确不能隐式转换 c.不正确，不能隐式转换 d.正确，函数结束时会释放掉p所指向内存。

12.13

p和sp所指向内存被释放掉

12.14 12.15

#include <cstdlib>#include <iostream>#include <vector>#include <string>#include <algorithm>#include <memory>using namespace std;struct destination{string name;};struct connection{connection(){};connection(string n):name(n){};string name;};void disconnect(connection c){cout << "disconnect " << c.name <<endl;}connection connect(destination * d){cout << "connect " << d->name << endl;connection a;return a;}void end_connection(connection *p){cout << "call endconnect" << endl;disconnect(*p);}void f(destination &d){connection c = connect(&d);//shared_ptr<connection>p(&c, end_connection);shared_ptr<connection>p(&c, [](connection *c){disconnect(*c); });}int main(int argc, char *argv[]){connection c;c.name = "connect a";destination b;b.name = "dest b";f(b);cout<< endl;system("PAUSE");return 0;}

12.16

错误 1 error C2280: “std::unique_ptr<std::string,std::default_delete<_Ty>> &std::unique_ptr<_Ty,std::default_delete<_Ty>>::operator =(const std::unique_ptr<_Ty,std::default_delete<_Ty>> &)”: 尝试引用已删除的函数d:\project\c++project\primer\c11\c11\main.cpp

12.17

a. 类型不匹配 ； b .会导致后续程序错误，一旦p1 = nullptr,则pi和ix的内存被释放掉，无法正常调用；c.同b，delete pi2后也无法正常调用p2；d.可以这样用；e.可以这样用；f.同b.

12.18

一旦share_ptr引用为0，就自动释放了。

12.19 12.20

#include <cstdlib>#include <iostream>#include <fstream>#include <vector>#include <string>#include <algorithm>#include <memory>using namespace std;class StrBlob{friend class StrBlobPtr;public:typedef vector<string>::size_type size_type;StrBlob();~StrBlob();StrBlob(initializer_list<string> il);size_type size() const { return data->size(); }bool empty() const { return data->empty(); }void push_back(const string &t){ data->push_back(t); }void pop_back();string& front();string& back();StrBlobPtr begin();StrBlobPtr end();private:shared_ptr<vector<string>> data;void check(size_type i, const string &msg) const;};class StrBlobPtr{public:StrBlobPtr() :curr(0){}StrBlobPtr(StrBlob &a, size_t sz = 0) :wptr(a.data), curr(sz){}string& deref() const;StrBlobPtr& incr();const size_t& getCurr() const;private:shared_ptr<vector<string>> check(size_t, const string&) const;weak_ptr<vector<string>> wptr;size_t curr;};StrBlobPtr StrBlob::begin(){return StrBlobPtr(*this);}StrBlobPtr StrBlob::end(){return StrBlobPtr(*this, data->size());};StrBlob::StrBlob() :data(make_shared<vector<string>>()){}StrBlob::~StrBlob(){}StrBlob::StrBlob(initializer_list<string> il) :data(make_shared<vector<string>>(il)){}void StrBlob::check(size_type i, const string &msg) const{if (i >= data->size()){throw out_of_range(msg);}}void StrBlob::pop_back(){check(0, "pop_back");data->pop_back();}string& StrBlob::front(){check(0, "front");return data->front();}string& StrBlob::back(){check(0, "back");return data->back();}shared_ptr<vector<string>> StrBlobPtr::check(size_t i, const string& msg) const{auto ret = wptr.lock();if (!ret)throw runtime_error("unbound StrBlobPtr");if (i >= ret->size()){throw out_of_range(msg);}return ret;}string& StrBlobPtr::deref() const{auto p = check(curr, "dereference past end");return (*p)[curr];}StrBlobPtr& StrBlobPtr::incr(){check(curr, "increment past end of StrBlobPtr");++curr;return *this;}const size_t& StrBlobPtr::getCurr() const{return curr;}int main(int argc, char *argv[]){string temp;ifstream in("type.txt");StrBlob sb;StrBlobPtr sbptr(sb);while (getline(in,temp)){sb.push_back(temp);}in.close();size_t c = 0;/*Hi, How are you today?I'am fine, tank you, and you?I'am fine too.GoodBye.Bye-Bye.*/while (sbptr.getCurr() != sb.size()){cout << sbptr.deref() << endl;sbptr.incr();}cout<< endl;system("PAUSE");return 0;}

12.21

我认为12.21这个版本好。简练。

12.22

在StrBlobPtr里面添加一个const的构造函数。

StrBlobPtr(const StrBlob &a, size_t sz = 0) :wptr(a.data), curr(sz){}

12.23

#include <cstdlib>#include <iostream>#include <vector>#include <string>#include <memory>using namespace std;const char* connectChars(const char* t1, const int s1, const char* t2, const int s2){int len = s1 + s2;char *t = new char[len];for (int i = 0; i != len; i++){if (i < s1){t[i] = t1[i];}else if (i >= s1){t[i] = t2[i-s1];}}for (int j = 0; j < len; j++){cout << t[j];}return t;}const string* connectString(const string &s1, const string &s2){string::size_type len = s1.length() + s2.length();string* p = new string[len]{string(s1+s2)};cout << *p;return p;}int main(int argc, char *argv[]){connectChars("123",3, "456",3);//123456cout << endl;connectString("123", "456");//123456cout << endl;system("PAUSE");return 0;}

12.24

#include <cstdlib>#include <iostream>#include <string>using namespace std;int main(int argc, char *argv[]){char* t = new char[2];cin >> t;for (int i = 0; i < 4; i++){cout << t[i];}cout << endl;system("PAUSE");

输入一个超出的没有发现有问题。

12.25

delete [] pa;

12.26

#include <cstdlib>#include <iostream>#include <vector>#include <string>#include <memory>using namespace std;int main(int argc, char *argv[]){size_t n = 5;string s;allocator<string> alloc;auto const p = alloc.allocate(n);auto q = p;while (cin >> s && q != p + n){alloc.construct(q, s);cout << (*q )<< endl;q++;}while (q != p){alloc.destroy(--q);}alloc.deallocate(p, n);cout << endl;system("PAUSE");return 0;}

12.27

因为不理解本节的意思，所以这个自己的版本有错误，不要参考。

#ifndef __Text_Query_H__#define __Text_Query_H__#include <vector>#include <string>#include <set>#include <map>#include <fstream>#include <iostream>#include <sstream>using namespace std;class TextQuery{public:TextQuery(ifstream&);TextQuery();void query(string word);protected:private:vector<string> lines;//保存每行文本set<unsigned int> lineNum;//保存查找单词对应的行号map<string, set<unsigned int>> wordsNum;//保存查找过单词的列表};#endif

#ifndef __Query_Result_H__#define __Query_Result_H__using namespace std;class QueryResult{public:QueryResult();~QueryResult();protected:private:};#endif

#include "TextQuery.h"TextQuery::TextQuery(ifstream& f){string line;while (getline(f,line)){lines.push_back(line);}}void TextQuery::query(string word){auto b = lines.begin();auto e = lines.end();vector<string>::iterator it = b;vector<string>::size_type len = lines.size();for (int i = 0; i < len; ++it,++i){istringstream record(*it);string tempw;while (record>>tempw){if (tempw == word){lineNum.insert(i);cout << i << endl;}}}}

#include <cstdlib>#include <iostream>#include "TextQuery.h"using namespace std;int main(int argc, char *argv[]){ifstream infile("a.txt");TextQuery tq(infile);tq.query("name");system("PAUSE");return 0;}

12.18

有个问题，同一行如果出现多次查询的单词，只记录一次。需要修改

#include <cstdlib>#include <iostream>#include <fstream>#include <sstream>#include <vector>#include <string>#include <map>#include <set>#include <memory>using namespace std;typedef vector<string>::size_type size_type;int main(int argc, char *argv[]){vector<string> lines;map<string, shared_ptr<set<vector<string>::size_type>>> wordsDic;shared_ptr<set<vector<string>::size_type>> p;string queryWord;ifstream in("type.txt");if (in){string line;while (getline(in, line)){cout << line << endl;lines.push_back(line);}while (true){if (!(cin >> queryWord) || queryWord == "q") break;if (wordsDic[queryWord] == nullptr){p = wordsDic[queryWord];p.reset(new set<size_type>);for (size_type i = 0; i < lines.size(); i++){istringstream s(lines.at(i));string temp;while (s>>temp){if (temp == queryWord){p->insert(i+1);}}}}cout << queryWord << " occurs " << p->size() << "times" << endl;for (auto t : (*p)){cout << "( line " << t << " ) " << lines.at(t-1) << endl;}}in.close();}cout << endl;system("PAUSE");return 0;}

12.29

用do...while();好，第一、代码更清晰，第二、保证输入的是"q"也能执行一次。（参考12.30)

12.30

头文件

TextQuery.h

#ifndef __Text_Query_H__#define __Text_Query_H__#include <vector>#include <string>#include <set>#include <map>#include <fstream>#include <iostream>#include <sstream>#include <memory>#include "QueryResult.h"using namespace std;class TextQuery{friend class QueryResult;public:TextQuery(ifstream&);TextQuery();void query(string);protected:private:vector<string> lines;//保存每行文本map<string, set<unsigned int>> wordsDic;//保存查找过单词的列表，这里set应该是这个指针类型，但是故意没有使用。shared_ptr<QueryResult> p;};#endif

QueryResult.h

#ifndef __Query_Result_H__#define __Query_Result_H__#include "TextQuery.h"using namespace std;class QueryResult{public:QueryResult();void print(const map<string,set<vector<string>::size_type>>&, const vector<string>&,string);protected:private:};#endif

源文件

#include "TextQuery.h"TextQuery::TextQuery(ifstream& f){string line;while (getline(f,line)){cout << line << endl;lines.push_back(line);}p = make_shared<QueryResult>();}void TextQuery::query(string word){for (vector<string>::size_type i = 0; i < lines.size(); i++){istringstream s(lines.at(i));string temp;shared_ptr<set<vector<string>::size_type>> p;if ((&wordsDic[word]) == nullptr)//假如此单词对应的行号列表为空{//这里是个陷阱，它存的是*p的拷贝,因为p在语句块结束时其内容就自动销毁了。//注意正常情况下，这里应该存一个set指针（参考书上例子）。p = make_shared<set<vector<string>::size_type>>();wordsDic[word] = *p;}while (s>>temp)//读取这行的单词{if (temp == word)//假如查找到对应的单词{//插入行号wordsDic[word].insert(i + 1);}}}//打印结果(故意使用相同名字p)TextQuery::p->print(this->wordsDic,this->lines,word);}

#include "QueryResult.h"void QueryResult::print(const map<string, set<vector<string>::size_type>>& mp, const vector<string>& vec, string word){cout << word << " occurs " << mp.at(word).size() << " times " << endl;for (auto t : mp.at(word)){cout << "( line " << t << " ) " << vec.at(t - 1) << endl;}}QueryResult::QueryResult(){}

#include <cstdlib>#include <iostream>#include "TextQuery.h"#include "QueryResult.h"using namespace std;void runQueries(ifstream &infile){TextQuery tq(infile);while (true){cout << "enter word to look for, or q to qiut: ";string s;if (!(cin >> s) || s == "q") break;tq.query(s);}}int main(int argc, char *argv[]){ifstream in("a.txt");runQueries(in);system("PAUSE");return 0;}