C++：如何复制 std::string *
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C++ : how to duplicate std::string *
提问by Jérémy Pouyet
How can I, in c++, duplicate a std::string * ?
我如何在 C++ 中复制 std::string * ？
I want to do something like that :
我想做这样的事情：
std::string *str1 = new std::string("test");
std::string *str2 = strdup(str1);
delete str1;
std::cout << *str2 << std::endl; // result = "test"
回答by juanchopanza
If you really must use pointers and dynamic allocation (most likely not), then
如果你真的必须使用指针和动态分配（很可能不是），那么
std::string *str2 = new std::string(*str1);
In real life,
在真实生活中，
std::string str1 = "test";
std::string str2 = str1;
回答by David Heffernan
I'm pretty sure that you should not be using pointers here. Using pointers forces you to manage the lifetime, protect against exceptions and so on. A world of needless pain.
我很确定你不应该在这里使用指针。使用指针迫使您管理生命周期、防止异常等。一个无谓痛苦的世界。
The code you ought to write is:
你应该写的代码是：
std::string str1 = "test";
std::string str2 = str1;
回答by Sebastian Redl
You just do
你只要做
std::string *str2 = new std::string(*str1);
But I have to ask why you're using pointers in the first place. What's wrong with
但是我首先要问你为什么要使用指针。怎么了
std::string str1 = "test";
std::string str2 = str1;
?
?
回答by Vlad from Moscow
You could do more simpler without calling new and delete. For example
如果不调用 new 和 delete，您可以做得更简单。例如
std::string *str1 = new std::string("test");
std::string *str2 = str1;
std::cout << *str2 << std::endl; // result = "test"
At least in your example if there is a possibility to access str1 after its deletion it would be better to write
至少在您的示例中，如果在删除 str1 后有可能访问它，那么最好编写
std::string *str1 = new std::string("test");
std::string *str2 = new std::string( *str1 );
delete str1;
str1 = nullptr;
std::cout << *str2 << std::endl; // result = "test"
