C++Primer第五版 10.3.4节练习

练习10.22：重写统计长度小于等于6的单词数量的程序，使用函数代替lambda。
答：见练习10.22.cpp

练习10.23：bind接受几个参数？
答：不一定，至少接受一个参数绑定。详见 P356 bind的参数一节

练习10.24：给定一个string,使用bind和check_size在一个int的vector中查找第一个大于string长度的值。
答：见 练习10.24.cpp

练习10.25：在10.3.2节（第349页）的练习中，编写了一个使用partition的biggies版本。使用check_size和bind重写此函数。
答：见 练习10.25.cpp

练习10.22

/**练习10.22*2015/8/20*问题描述：练习10.22：重写统计长度小于等于6的单词数量的程序，使用函数代替lambda。*说明:对bind的使用*作者：Nick Feng*邮箱：[e-mail] */#include <iostream>#include <vector>#include <string>#include <algorithm>#include <functional>using namespace std;using namespace std::placeholders;bool check_size(const string &s, string::size_type sz){    return s.size() <= sz;}int main(){    vector<string> words = {"there","is","frog","living","in","the","lake"};    vector<string>::size_type sz = 6;    int cnt1 = count_if(words.begin(),words.end(),[sz](const string &s){return s.size() > sz ;}); //长度大于6的     cout << "total numbers of words is: " << cnt1 << endl;    auto check6 = bind(check_size,_1,sz);    int cnt = count_if(words.begin(), words.end(),check6);                                         cout << "total numbers of words is: " << cnt << endl;    return 0;}

练习10.24

/**练习10.24*2015/8/20*问题描述：练习10.24：给定一个string,使用bind和check_size在一个int的vector中查找第一个大于string长度的值。*说明：对于bind的理解，以及和比较对象的理解，比较的对象是什么类型，那么占位符就应该是哪个，check_size没有变，变得是bind的占位符*作者：Nick Feng*邮箱：[e-mail] */#include <iostream>#include <string>#include <algorithm>#include <vector>#include <functional>using namespace std;using namespace std::placeholders;bool check_size(const string &s,string::size_type sz){    return sz > s.size();}int main(){    vector<int> words = {1,2,3,4,5,6,7};     string word = "happy";    cout << "word is: " << word << "    size is:" << word.size() << endl;    auto f=[]() {cout << "1 2 3 4 5 6 7";};     cout << "numbers : ";    f();    cout << endl;    auto check5 = bind(check_size,word,_1);    auto wc = find_if(words.begin(), words.end(),check5);    cout << "First number which is bigger than s.size() is:" << endl;    cout << *wc << endl;    return 0;}

练习10.25

/**练习10.25*2015/8/20*问题描述：练习10.25：在10.3.2节（第349页）的练习中，编写了一个使用partition的biggies版本。使用check_size和bind重写此函数。*说明：学会用bind这一特性，在练习10.19基础上修改 *作者：Nick Feng *邮箱：[e-mail] *//**练习10.19*2015/8/18 *问题描述：练习10.19：用stable_partition重写前一题的程序，与stable_sort类似，在划分后的序列中维持原有元素的顺序。*说明：在练习10.18的基础上改动，与原来程序不同的地方，stable_partition后，单词顺序和之前一致 *作者：Nick Feng *邮箱：[e-mail] *//**练习10.18 *2015/8/18 *问题描述：练习10.18：重写biggies，用partition代替find_if。我们在10.3.1节练习10.13（第345页）中介绍了partition算法。*说明：在练习10.16的基础上改动 *作者：Nick Feng *邮箱：[e-mail] *//**练习10.16 *2015/8/18 *问题描述：练习10.16：使用lambda编写你自己版本的biggies。 *说明：复习前面elimDups的写法，make_plural参考了201页写法，书上说得很清楚 *作者：Nick Feng *邮箱：[e-mail] */#include <iostream>#include <vector>#include <algorithm>#include <string>#include <functional>using namespace std;using namespace std::placeholders;bool isShorter(const string &s1, const string &s2){    return s1.size() < s2.size();}void elimDups(vector<string> words){    stable_sort(words.begin(), words.end(),isShorter);    auto end_unique = unique(words.begin(), words.end());    words.erase(end_unique, words.end()); }bool check_size(const string &s, string::size_type sz){    return s.size() < sz;}string make_plural(size_t ctr, const string &word, const string &ending){    return (ctr > 1) ? word + ending : word;}void biggies(vector<string> &words, vector<string>::size_type sz){    elimDups(words);    stable_sort(words.begin(), words.end(),[](const string &a, const string &b){return a.size() < b.size();});    //auto wc = find_if(words.begin(), words.end(),[sz](const string &a){return a.size() >= sz;});    //auto wc = partition(words.begin(), words.end(),[sz](const string &a){return a.size() < sz;});//使用partition代替find_if函数     //auto wc = stable_partition(words.begin(), words.end(),[sz](const string &a){return a.size() < sz;});//使用stable_partition代替partition     auto check = bind(check_size,_1,sz);//2015/8/20改动 使用bind check_size     auto wc = stable_partition(words.begin(), words.end(),check);    auto count = words.end() - wc;    cout << count << " " << make_plural(count,"word", "s") << " of length " << sz << " or longer" << endl;    for_each(wc, words.end(),[](const string &s){cout << s << " ";});    cout << endl;}int main(){    vector<string> words = {"the","quick","red","fox","jumps","over","the","slow","red","turtle"};    vector<string>::size_type sz = 5;    biggies(words,sz);    return 0;}