【C++ Primer 第十二章】 unique_ptr动态内存与智能指针

shared_ptr类

 1 /* StrBlob.H */
 2 
 3 #include<iostream>
 4 #include<string>
 5 #include<vector>
 6 #include<memory>
 7 #include<initializer_List>
 8 using namespace std;
 9 
10 class StrBlob {
11 public:
12     typedef vector<string>::size_type size_type;
13     StrBlob();
14     StrBlob(initializer_list<vector<string>> il);
15 
16     void check(int i, const string & msg) const;
17 
18     bool empty() { return data->empty(); }
19     size_type size() const { return data->size(); }
20     void push_back(const string &t) { data->push_back(t); }
21 
22     string &front();
23     string &back();
24     void pop_back();
25     
26 private:
27     shared_ptr<vector<string>> data;
28     void check(int i, const string &msg) const;
29 };
30 
31 StrBlob::StrBlob(): data(make_shared<vector<string>>()) {}
32 
33 StrBlob::StrBlob(initializer_list<vector<string>> il): data(make_shared<vector<string>>(il)) {}
34 
35 void StrBlob::check(int i, const string &msg) const
36 {
37     if (i >= data->size())
38         throw out_of_range(msg);
39 }
40 
41 string &StrBlob::front() 
42 {
43     check(0, "front on empty StrBlob");
44     return data->front();
45 }
46 
47 string &StrBlob::back() 
48 {
49     check(0, "back on empty StrBlob");
50     return data->back();
51 }
52 
53 void StrBlob::pop_back()
54 {
55     check(0, "pop_back on empty StrBlob");
56     data->pop_back();
57 }