C++Primer

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12.2

#ifndef MY_STRBLOB_H#define MY_STRBLOB_H#include<vector>#include<string>#include<initializer_list>#include<memory>#include<stdexcept>using namespace std;class StrBlob{public:    typedef vector<string>::size_type size_type;    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(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);}string& StrBlob::front(){    check(0, "front on empty StrBlob");    return data->front();}const string& StrBlob::front() const{    check(0, "front on empty StrBlob");    return data->front();}string& StrBlob::back(){    check(0, "back on empty StrBlob");    return data->back();}const string& StrBlob::back() const{    check(0, "back on empty StrBlob");    return data->back();}void StrBlob::pop_back(){    check(0, "pop_back on empty StrBlob");    data->pop_back();}#endif

测试

#include<iostream>using namespace std;#include "my_StrBlob.h"int main(int argc,char **argv){    StrBlob b1;    {        StrBlob b2 = { "a","an","the" };        b1 = b2;        b2.push_back("about");        cout << b2.size() << endl;    }    cout << b1.size() << endl;    cout << b1.front() << " " << b1.back() << endl;    const StrBlob b3 = b1;    cout <<b3.front() << " " << b3.back() << endl;    return 0;}

12.6

#include<iostream>#include<vector>using namespace std;vector<int> *new_vector(void){    return new (nothrow)vector<int>;}void read_ints(vector<int>*pv){    int v;    while (cin >> v)    {        pv->push_back(v);    }}void print_ints(vector<int> *pv){    for (const auto &v : *pv)    {        cout << v << " ";    }    cout << endl;}int main(){    vector<int> *pv = new_vector();    if (!pv)    {        cout << "内存不足！" << endl;        return -1;    }    read_ints(pv);    print_ints(pv);    delete pv;    pv = nullptr;    return 0;}

12.14

#include<iostream>#include<vector>#include<memory>using namespace std;struct destination{ };struct connection{ };connection connect(destination *pd){    cout << "打开连接" << endl;    return connection();}void disconnect(connection c){    cout << "关闭连接" << endl;}void f(destination &d){    cout << "直接管理connect" << endl;    connection c = connect(&d);    cout << endl;}void end_connection(connection *p) { disconnect(*p); }void f1(destination &d){    cout << "用shared_ptr管理connect" << endl;    connection c = connect(&d);    shared_ptr<connection> p(&c, end_connection);    cout << endl;}int main(int argc,char**argv){    destination d;    f(d);    f1(d);    return 0;}

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