c++ - 如果在 main 中使用字符串，为什么 CRT 会返回 8 字节泄漏？

Question

#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <fstream>
#include <vector>
#include <stdlib.h>
#include <crtdbg.h>

#define _CRTDBG_MAP_ALLOC

using namespace std;

int main(void){
    string file = "hello";
    string foo;
    char response;

    _CrtDumpMemoryLeaks();
    _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
    _CrtSetReportMode(_CRT_ERROR, _CRTDBG_MODE_DEBUG);

    return 0;
}

只是一个独立的小例子。控制台将显示:

Detected memory leaks!
Dumping objects ->
{143} normal block at 0x007DAE50, 8 bytes long.
 Data: <  B     > 18 FB 42 00 00 00 00 00 
{142} normal block at 0x007DAE08, 8 bytes long.
 Data: << B     > 3C FB 42 00 00 00 00 00 

运行后。这是 CRT 未正确处理字符串的问题吗？

Answer 1

这是因为您在 main 返回之前调用了 _CrtDumpMemoryLeaks，所以字符串还没有超出范围。你应该只在字符串应该被释放后检查泄漏，例如:

void myFunc() {
    string file = "hello";
    string foo;
    char response;
}

int main(void){

    myFunc();

    _CrtDumpMemoryLeaks();
    _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
    _CrtSetReportMode(_CRT_ERROR, _CRTDBG_MODE_DEBUG);

    return 0;
}