我是智能指针世界的新手.我已经完成了我的阅读,他们都表示,智能指针将避免漏掉内存,即使程序在遇到异常后也会退出.
我写了一个简单的程序来尝试这个,但是Valgrind告诉我我的程序是泄漏的内存(三个分配,只有一个免费).
这是源代码：
#include <iostream>
#include <memory>
using namespace std;
int main()
{
auto_ptr<int> ptr_int(new int(5));
throw std::bad_alloc();
cout << *ptr_int;
}
这个Valgrind报告：
==27862== Memcheck,a memory error detector ==27862== Copyright (C) 2002-2010,and GNU GPL'd,by Julian Seward et al. ==27862== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info ==27862== Command: ./smart_pointers ==27862== Parent PID: 5388 ==27862== ==27862== ==27862== HEAP SUMMARY: ==27862== in use at exit: 104 bytes in 2 blocks ==27862== total heap usage: 3 allocs,1 frees,120 bytes allocated ==27862== ==27862== 4 bytes in 1 blocks are still reachable in loss record 1 of 2 ==27862== at 0x4026351: operator new(unsigned int) (vg_replace_malloc.c:255) ==27862== by 0x804878A: main (smart_pointers.cpp:8) ==27862== ==27862== 100 bytes in 1 blocks are possibly lost in loss record 2 of 2 ==27862== at 0x4025BD3: malloc (vg_replace_malloc.c:236) ==27862== by 0x40E861A: __cxa_allocate_exception (in /usr/lib/libstdc++.so.6.0.14) ==27862== by 0x80487AE: main (smart_pointers.cpp:10) ==27862== ==27862== LEAK SUMMARY: ==27862== definitely lost: 0 bytes in 0 blocks ==27862== indirectly lost: 0 bytes in 0 blocks ==27862== possibly lost: 100 bytes in 1 blocks ==27862== still reachable: 4 bytes in 1 blocks ==27862== suppressed: 0 bytes in 0 blocks ==27862== ==27862== For counts of detected and suppressed errors,rerun with: -v ==27862== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 19 from 8)
使用智能指针确保分配的资源将被破坏,即使出现异常？
解决方法
当调用
std::terminate()(如未捕获的异常情况)时,正常的清理不会运行(至少对于main()的堆栈帧),因此您在堆栈帧中分配的内存泄漏,甚至虽然它应该由智能指针来管理.当你在main()中捕获std :: bad_alloc,并且返回正常时,智能指针就可以做到这一点了.
