C++ Primer(第5版) 练习 12.2
练习 12.2 编写你自己的StrBlob类,包含const版本的front和back。
环境:Linux Ubuntu(云服务器)
工具:vim
代码块
cpp
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();
string &back();
string &front() const;
string &back() const;
private:
shared_ptr<vector<string>> data;
void check(size_type i, const string &msg) const;
};
void StrBlob::pop_back(){
check(0, "pop_back on empty StrBlob");
data->pop_back();
}
string& StrBlob::front(){
check(0, "front on empty StrBlob");
return data->front();
}
string& StrBlob::back(){
check(0, "back on empty StrBlob");
return data->back();
}
string& StrBlob::front() const{
check(0, "front on empty StrBlob");
return data->front();
}
string& StrBlob::back() const{
check(0, "back on empty StrBlob");
return data->back();
}
void StrBlob::check(size_type i, const string &msg) const{
if(i >= data->size()){
throw out_of_range(msg);
}
}