将 std::string 转换为 LPCSTR 时的奇怪行为 [英] Weird behavior while converting a std::string to a LPCSTR

问题描述

当我在将 std::string 转换为 LPCSTR 时偶然发现一个奇怪的行为时，我正在玩一些字符串.

I was playing with some strings when I stumbled upon a weird behavior while converting a std::string to a LPCSTR.

我编写了一个小型测试应用程序来演示:

I have written a small test application to demonstrate :

#include <string>
#include <Windows.h>
#include <iostream>

using namespace std;

int main ()
{
    string stringTest = (string("some text") + " in addition with this other text").c_str(); 
    LPCSTR lpstrTest= stringTest.c_str();
    cout << lpcstrTest << '\n';

    cout << (string("some text") + " in addition with this other text").c_str() << '\n';

    LPCSTR otherLPCSTR= (string("some text") + " in addition with this other text").c_str();
    cout << otherLPSTR;
}

这是输出:

some text in addition with this other text
some text in addition with this other text
îþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþîþ...[more unreadable stuff]...

我只是想知道是什么导致了这种奇怪的行为.

I am simply wondering what is causing this strange behavior.

谢谢

推荐答案

LPCSTR otherLPCSTR= (string("some text") + " in addition with this other text").c_str();
cout << otherLPSTR;

部分

 (string("some text") + " in addition with this other text")

创建一个所谓的临时"对象，该对象没有名称并在包含它的语句完成时被销毁.你从中得到 c_str() ，它指向那个临时对象的一些内部存储.您将该 c_str() 分配给 otherLPCSTR 变量.之后，包含临时字符串的语句"结束，临时字符串被销毁，otherLPCSTR指向nowhere".

creates a so-called "temporary" object, which has no name and gets destructed when the statement that contains it finishes. You get the c_str() from that, which points to some internal storage of that temporary object. You assign that c_str() to the otherLPCSTR variable. After that, "the statment that contains the temporary string" has finished, so the temporary string gets destructed, and the otherLPCSTR points "nowhere".

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