标签: memory-leaks

所以我有这个程序在我的家用机器上编译很好,但是一旦我在大学服务器上编译它就会打破......:/这对我的屁股来说是一个巨大的痛苦.我不知道可能导致错误的位置或原因.我首先从大学的valgrind报告开始.

    ==13527== Memcheck, a memory error detector
==13527== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==13527== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==13527== Command: ./main stock.dat coins.dat
==13527== 
==13527== Invalid write of size 8
==13527==    at 0x402762: load_data (in /RMIThome/shr/5/s3234575/Assignments2/main)
==13527==    by 0x4028BE: main (in /RMIThome/shr/5/s3234575/Assignments2/main)
==13527==  Address 0x6172676f72502074 is not stack'd, malloc'd or (recently) free'd
==13527== 
==13527== 
==13527== Process terminating with default action of signal 11 (SIGSEGV)
==13527==  General Protection Fault …

这是C++中的一段简单代码,它只为一个名为Foo的类的实例动态分配内存,并且忘记以后释放内存.让我们假设Foo非常简单.

int main() {
  Foo *abcd = new Foo();
  return 0;
}

由于程序终止,它真的是内存泄漏吗？如果我重新运行此程序,先前分配的内存是否可用于分配？

这是等效的Java代码:

public static void main(String[] args) {
  Foo abcd = new Foo();
}

由于程序快速终止,如果垃圾收集器没有足够的时间来释放内存怎么办？如果我重新运行此程序,先前分配的内存是否可用于分配？

甚至

int
main () {
  return 0;
}

泄漏记忆.确实,运行valgrind [0]输出

==21013== HEAP SUMMARY:
==21013==     in use at exit: 72,704 bytes in 1 blocks
==21013==   total heap usage: 1 allocs, 0 frees, 72,704 bytes allocated
==21013== 
==21013== LEAK SUMMARY:
==21013==    definitely lost: 0 bytes in 0 blocks
==21013==    indirectly lost: 0 bytes in 0 blocks
==21013==      possibly lost: 0 bytes in 0 blocks
==21013==    still reachable: 72,704 bytes in 1 blocks
==21013==         suppressed: 0 bytes in 0 blocks

为什么会这样？如果Valgrind应该使用c ++进行泄漏检查失败,我应该如何亲自检查内存泄漏？

[0], …

在测试文档中,我发现我被问到以下代码中的问题是:

#include <iostream>
#include <stdlib.h>
#include <string.h>
using namespace std;

int main()
{
    char* a = (char*) malloc (20);
    char* b = (char*) malloc (20);
    strcpy(b, "Secure Coding");
    strcpy(a, "Insecure Coding");
    a = b;
    cout << a << endl;
    cout << b << endl << endl;
    free(a);
    free(b);
    return 0;
}

它是什么？