又讨厌又喜欢的宏

[kong361]

以下的宏是什么意思,有什么用,先谢了.
======================================================================
在 *.cpp 里面

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
======================================================================
在 *.h 里面

#if !defined(AFX_APPRISEINFO_H__ABA3BD0C_368A_4756_839A_09515257083F__INCLUDED_)
#define AFX_APPRISEINFO_H__ABA3BD0C_368A_4756_839A_09515257083F__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif
======================================================================

[taianmonkey]

THIS_FILE
Remarks

This macro expands to the name of the file that is being compiled. The information is used by the ASSERT and VERIFY macros. AppWizard and ClassWizard place the macro in source code files they create.

Example

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

// __FILE__ is one of the six predefined ANSI C macros that the
// compiler recognizes.

[abc_xyz]

如果define了_DEBUG,就编译
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
代码;

如果没有define (AFX_APPRISEINFO_H__ABA3BD0C_368A_4756_839A_09515257083F__INCLUDED_)
就编译
#define AFX_APPRISEINFO_H__ABA3BD0C_368A_4756_839A_09515257083F__INCLUDED_

#if _MSC_VER > 1000
#pragma once
代码

[jmcooler]

最好看看MSDN文档，这些都有解释。