当字符串超出范围时将 string::c_str() 分配给 const char*

assigning string::c_str() to a const char* when the string goes out of scope(当字符串超出范围时将 string::c_str() 分配给 const char*)

问题描述

我对基本的 C++ 用法有疑问.下面的代码，用 gcc/LInux 编译，打印正确.

I have a doubt on basic C++ usage. The code below, compiled with gcc/LInux, prints out correctly.

字符串 test 超出范围，所以它的 c_str() 值也应该是无效的，不是吗?我错了还是我误解了 const char* 的含义?

The string test goes out of scope so also its c_str() value should be invalid isn't it? Am I wrong or do I have misunderstood the const char*meaning?

   #include <iostream>
   int main(){
     const char* a = "aaaa";
       std::cout << a;
       { std::string test("bbbb");a=test.c_str();}
       std::cout << a;
       a = "cccc";
       std::cout << a;
   }


   aaaabbbbcccc
   // print out without any problem

推荐答案

你是对的，你的代码是无效的，因为它使用了一个生命周期已经结束的对象.它偶然"起作用，你不能依赖它.

You're right, your code is not valid since it uses an object whose lifetime has already ended. It works "by accident", you cannot rely on that.

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