关于一个内存泄露的问题-白红宇的个人博客

关于一个内存泄露的问题

发布日期：2022-02-07 06:39:47 浏览次数：2 分类：技术文章

本文共 5067 字，大约阅读时间需要 16 分钟。

是这样子的

这样子的代码居然能够正常运行

#include 
   
    #include 
    
     using namespace std;vector
     
      ::iterator fun(vector
      
         t){  return t.begin()+2;//返回一个局部对象的迭代器}int main(){  vector
       
         test = {
  1,2,3,4};  auto p1 = fun(test);  cout << *p1 << endl;//对之前局部的迭代器进行解引用，应该是不行的}// 但是能够正常的输出3

不清楚为什么

使用内存检测工具检查了一下

valgrind --tool=memcheck --leak-check=full --show-reachable=yes ./test.out==4677== Memcheck, a memory error detector==4677== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.==4677== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info==4677== Command: ./test.out==4677== ==4677== Invalid read of size 4==4677==    at 0x400BA8: main (t.cpp:13)==4677==  Address 0x5ab4cd8 is 8 bytes inside a block of size 16 free'd==4677==    at 0x4C2F160: operator delete(void*) (vg_replace_malloc.c:576)==4677==    by 0x4016AB: __gnu_cxx::new_allocator
   
    ::deallocate(int*, unsigned long) (new_allocator.h:110)==4677==    by 0x4015B8: std::allocator_traits
    
     
       >::deallocate(std::allocator
      
       &, int*, unsigned long) (alloc_traits.h:517)==4677==    by 0x4013A5: std::_Vector_base

>::_M_deallocate(int*, unsigned long) (stl_vector.h:178)==4677== by 0x401094: std::_Vector_base

>::~_Vector_base() (stl_vector.h:160)==4677== by 0x400EB2: std::vector

>::~vector() (stl_vector.h:425)==4677== by 0x400B9B: main (t.cpp:12)==4677== Block was alloc'd at==4677== at 0x4C2E1D6: operator new(unsigned long) (vg_replace_malloc.c:334)==4677== by 0x4016EF: __gnu_cxx::new_allocator

::allocate(unsigned long, void const*) (new_allocator.h:104)==4677== by 0x40160D: std::allocator_traits

>::allocate(std::allocator

&, unsigned long) (alloc_traits.h:491)==4677== by 0x401435: std::_Vector_base

>::_M_allocate(unsigned long) (stl_vector.h:170)==4677== by 0x401508: std::_Vector_base

#include

using namespace std;vector

::iterator fun(vector

& t){

//修改了，变成传引用 return t.begin()+2;}int main(){ vector

test = {

1,2,3,4}; auto p1 = fun(test); cout << *p1 << endl;}

valgrind --tool=memcheck --leak-check=full --show-reachable=yes ./test.out==4743== Memcheck, a memory error detector==4743== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.==4743== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info==4743== Command: ./test.out==4743== 3==4743== ==4743== HEAP SUMMARY:==4743== in use at exit: 72,704 bytes in 1 blocks==4743== total heap usage: 3 allocs, 2 frees, 73,744 bytes allocated==4743== ==4743== 72,704 bytes in 1 blocks are still reachable in loss record 1 of 1==4743== at 0x4C2DBB6: malloc (vg_replace_malloc.c:299)==4743== by 0x4EC2EFF: ??? (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)==4743== by 0x40104E9: call_init.part.0 (dl-init.c:72)==4743== by 0x40105FA: call_init (dl-init.c:30)==4743== by 0x40105FA: _dl_init (dl-init.c:120)==4743== by 0x4000CF9: ??? (in /lib/x86_64-linux-gnu/ld-2.23.so)==4743== ==4743== LEAK SUMMARY:==4743== definitely lost: 0 bytes in 0 blocks==4743== indirectly lost: 0 bytes in 0 blocks==4743== possibly lost: 0 bytes in 0 blocks==4743== still reachable: 72,704 bytes in 1 blocks==4743== suppressed: 0 bytes in 0 blocks==4743== ==4743== For counts of detected and suppressed errors, rerun with: -v==4743== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

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