/**//*****************************************************************
* ?000 Microsoft Corporation *
* CRT_DBG1 *
* This simple program illustrates the basic debugging features *
* of the C runtime libraries, and the kind of debug output *
* that these features generate. *
*****************************************************************/
#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <crtdbg.h>
// Disable deprecation warnings. The unsecure version of strcpy is
// used intentionally to show off debugging features.
#pragma warning (disable : 4996)
// This routine place comments at the head of a section of debug output
void OutputHeading( const char * explanation )
{
_RPT1( _CRT_WARN, "\n\n%s:\n**************************************\
************************************\n", explanation );
}
// The following macros set and clear, respectively, given bits
// of the C runtime library debug flag, as specified by a bitmask.
#ifdef _DEBUG
#define SET_CRT_DEBUG_FIELD(a) \
_CrtSetDbgFlag((a) | _CrtSetDbgFlag(_CRTDBG_REPORT_FLAG))
#define CLEAR_CRT_DEBUG_FIELD(a) \
_CrtSetDbgFlag(~(a) & _CrtSetDbgFlag(_CRTDBG_REPORT_FLAG))
#else
#define SET_CRT_DEBUG_FIELD(a) ((void) 0)
#define CLEAR_CRT_DEBUG_FIELD(a) ((void) 0)
#endif
int main( )
{
char *p1, *p2;
_CrtMemState s1, s2, s3;
#ifndef _DEBUG
printf("Skipping this for non-debug mode.\n");
return 2;
#endif
// Send all reports to STDOUT
_CrtSetReportMode( _CRT_WARN, _CRTDBG_MODE_FILE );
_CrtSetReportFile( _CRT_WARN, _CRTDBG_FILE_STDOUT );
_CrtSetReportMode( _CRT_ERROR, _CRTDBG_MODE_FILE );
_CrtSetReportFile( _CRT_ERROR, _CRTDBG_FILE_STDOUT );
_CrtSetReportMode( _CRT_ASSERT, _CRTDBG_MODE_FILE );
_CrtSetReportFile( _CRT_ASSERT, _CRTDBG_FILE_STDOUT );
// Allocate 2 memory blocks and store a string in each
p1 = malloc( 34 );
strcpy( p1, "This is the p1 string (34 bytes)." );
p2 = malloc( 34 );
strcpy( p2, "This is the p2 string (34 bytes)." );
OutputHeading(
"Use _ASSERTE to check that the two strings are identical" );
_ASSERTE( strcmp( p1, p2 ) == 0 );
OutputHeading(
"Use a _RPT macro to report the string contents as a warning" );
_RPT2( _CRT_WARN, "p1 points to '%s' and \np2 points to '%s'\n", p1, p2 );
OutputHeading(
"Use _CRTMemDumpAllObjectsSince to check the p1 and p2 allocations" );
_CrtMemDumpAllObjectsSince( NULL );
free( p2 );
OutputHeading(
"Having freed p2, dump allocation information about p1 only" );
_CrtMemDumpAllObjectsSince( NULL );
// Store a memory checkpoint in the s1 memory-state structure
_CrtMemCheckpoint( &s1 );
// Allocate another block, pointed to by p2
p2 = malloc( 38 );
strcpy( p2, "This new p2 string occupies 38 bytes.");
// Store a 2nd memory checkpoint in s2
_CrtMemCheckpoint( &s2 );
OutputHeading(
"Dump the changes that occurred between two memory checkpoints" );
if ( _CrtMemDifference( &s3, &s1, &s2 ) )
_CrtMemDumpStatistics( &s3 );
// Free p2 again and store a new memory checkpoint in s2
free( p2 );
_CrtMemCheckpoint( &s2 );
OutputHeading(
"Now the memory state at the two checkpoints is the same" );
if ( _CrtMemDifference( &s3, &s1, &s2 ) )
_CrtMemDumpStatistics( &s3 );
strcpy( p1, "This new p1 string is over 34 bytes" );
OutputHeading( "Free p1 after overwriting the end of the allocation" );
free( p1 );
// Set the debug-heap flag so that freed blocks are kept on the
// linked list, to catch any inadvertent use of freed memory
SET_CRT_DEBUG_FIELD( _CRTDBG_DELAY_FREE_MEM_DF );
p1 = malloc( 10 );
free( p1 );
strcpy( p1, "Oops" );
OutputHeading( "Perform a memory check after corrupting freed memory" );
_CrtCheckMemory( );
// Use explicit calls to _malloc_dbg to save file name and line number
// information, and also to allocate Client type blocks for tracking
p1 = _malloc_dbg( 40, _NORMAL_BLOCK, __FILE__, __LINE__ );
p2 = _malloc_dbg( 40, _CLIENT_BLOCK, __FILE__, __LINE__ );
strcpy( p1, "p1 points to a Normal allocation block" );
strcpy( p2, "p2 points to a Client allocation block" );
// You must use _free_dbg to free a Client block
OutputHeading(
"Using free( ) to free a Client block causes an assertion failure" );
free( p1 );
free( p2 );
p1 = malloc( 10 );
OutputHeading( "Examine outstanding allocations (dump memory leaks)" );
_CrtDumpMemoryLeaks( );
// Set the debug-heap flag so that memory leaks are reported when
// the process terminates. Then, exit.
OutputHeading( "Program exits without freeing a memory block" );
SET_CRT_DEBUG_FIELD( _CRTDBG_LEAK_CHECK_DF );
}
大概解釋一下，這里的函數(shù)都是什么作用：
1、首先是剛開始的六個函數(shù)，這六個函數(shù)的作用就是讓接下來的內(nèi)存調(diào)試函數(shù)輸出調(diào)試信息到控制臺。后面的函數(shù)都是實(shí)際調(diào)試內(nèi)存的，如果之前調(diào)用了這六個函數(shù)，那么調(diào)試信息會輸出到控制臺。
2、_CrtMemDumpAllObjectsSince( NULL )函數(shù)的作用是輸出目前為止，在堆中申請的空間的所有信息，包括地址，大小，內(nèi)容。
3、_CrtDumpMemoryLeaks( )函數(shù)的作用是檢測到目前為止，還有哪些堆中申請的內(nèi)存沒有釋放，包括地址，大小等
4、SET_CRT_DEBUG_FIELD( _CRTDBG_LEAK_CHECK_DF )宏的作用是在程序結(jié)束的時候檢測堆內(nèi)存是否還有泄露，作用同CrtDumpMemoryLeaks( )一樣，只不過是在所有該釋放的都結(jié)束之后，進(jìn)行最后的檢查。
（未完，以后補(bǔ)充）