c++重载new操作符,防止内存泄露

在c++开发过程中,内存泄漏是令程序员最苦恼的事情,有时为了找到一个内存泄漏的地方,要调试很长时间。重载new操作符,往往是很多大型项目常用的防内存泄漏的手段。本人闲来无事,写了个new操作符重载的函数,大家互相学习,有不足之处还望大家给予指正。

上代码,就不做过多的解释啦。

  1 #ifndef _BASE_H_
  2 #define _BASE_H_
  3 
  4 #include 
  5 #include 
  6 #include 
  7 using namespace std;
  8 
  9 typedef struct {
 10     unsigned long address;
 11     unsigned long size;
 12     char file[64];
 13     unsigned long line;
 14 } ALLOC_INFO;
 15 
 16 typedef maplong, ALLOC_INFO*> AllocMap;
 17 
 18 AllocMap* allocMap;
 19 
 20 #ifdef _DEBUG
 21 #define DEBUG_NEW new(__FILE__, __LINE__)
 22 
 23 void AddTrack(unsigned long addr, unsigned long asize, const char *fname, unsigned long lnum) 
 24 { 
 25     ALLOC_INFO *info = new ALLOC_INFO();
 26     info->address = addr;
 27     strncpy(info->file, fname, 63);
 28     info->line = lnum;
 29     info->size = asize;
 30     if (!allocMap)
 31     {
 32         allocMap = new AllocMap;
 33     }
 34     allocMap->insert(make_pair(addr,info));
 35 }
 36 
 37 void RemoveTrack(unsigned long addr)
 38 {
 39     if(!allocMap || 0 == allocMap->size())
 40     {
 41         return;
 42     }
 43     AllocMap::iterator iter = allocMap->find(addr);
 44     if (iter != allocMap->end())
 45     {
 46         ALLOC_INFO* info = iter->second;
 47         delete info;
 48         allocMap->erase(iter);
 49     }
 50 }
 51 
 52 inline void * operator new(unsigned int size, const char *file, int line)
 53 {
 54     void *ptr = (void *)malloc(size);
 55     AddTrack((unsigned long)ptr, size, file, line);
 56     return(ptr);
 57 }
 58 
 59 inline void operator delete(void *p)
 60 {
 61     RemoveTrack((unsigned long)p);
 62     free(p);
 63 }
 64 
 65 inline void * operator new[](unsigned int size, const char *file, int line)
 66 {
 67     void *ptr = (void *)malloc(size);
 68     AddTrack((unsigned long)ptr, size, file, line);
 69     return(ptr);
 70 }
 71 
 72 inline void operator delete[](void *p)
 73 {
 74     RemoveTrack((unsigned long)p);
 75     free(p);
 76 }
 77 #else  // _DEBUG
 78 #define DEBUG_NEW new
 79 #endif // _DEBUG
 80 
 81 // 用于检测内存并做最后的内存清理
 82 void DumpUnfreed()
 83 {
 84     AllocMap::iterator iter;
 85     ALLOC_INFO* info;
 86     unsigned long totalSize = 0;
 87     if(!allocMap || 0 == allocMap->size())
 88     {
 89         return;
 90     }
 91 
 92     for(iter = allocMap->begin(); iter != allocMap->end(); iter++)
 93     {
 94         printf("%-50s: LINE %d, ADDRESS %d %d unfreed\n", iter->second->file, iter->second->line
 95                , iter->second->address, iter->second->size);
 96         totalSize += iter->second->size;
 97         info = iter->second;
 98         delete info;
 99     }
100     printf("----------------------------------------------------------- \n");
101     printf("Total Unfreed: %d bytes \n", totalSize);
102     delete allocMap;
103 };
104 
105 #endif // _BASE_H_
复制代码
1 #include "base.h"
2 #define new DEBUG_NEW
3 
4 int main()
5 {
6     char* pszCeshi = new char[5];
7     DumpUnfreed();
8     return 0;
9 }
复制代码

最终运行结果如下:

c:\c++\test\test\main.cpp                         : LINE 6, ADDRESS 6637816 5 unfreed
-----------------------------------------------------------
Total Unfreed: 5 bytes

有些编译器会报:warning C4291: “void *operator new(unsigned int,const char *,int)”: 未找到匹配的删除运算符;如果初始化引发异常,则不会释放内存

要防止这种报错,可以再定义两个delete方法。如下:

inline void operator delete(void *p , const char *file, int line)
{
    RemoveTrack((unsigned long)p);
    free(p);
}

inline void operator delete[](void *p, const char *file, int line)
{
    RemoveTrack((unsigned long)p);
    free(p);
}

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