#define的作用域/作用范围
By Minidxer | October 16, 2007
#define可谓是从小用到大……(汗,夸张了点……），不过一直没有去考虑过它的作用范围，随手写了个程序测试了一下，结果是作用域的概念同样可以适用于#define，还是用代码说话吧。
用VC创建一个工程，加入下面文件
//class1.cpp
#include “stdafx.h”
#ifdef DEF_TEST_DEFINE_00
#pragma message(”DEF_TEST_DEFINE_00 was defined! Found in class1.cpp!”)
#endif
#ifdef DEF_TEST_DEFINE_11
#pragma message(”DEF_TEST_DEFINE_11 was defined(before)! Found in class1.cpp!”)
#endif
static int onlyTest(void)
{
#define DEF_TEST_DEFINE_11
return 0;
}
#ifdef DEF_TEST_DEFINE_11
#pragma message(”DEF_TEST_DEFINE_11 was defined(after)! Found in class1.cpp!”)
#endif
//end of class1.cpp
//class2.cpp
#include “stdafx.h”
#define DEF_TEST_DEFINE_00
#ifdef DEF_TEST_DEFINE_00
#pragma message(”DEF_TEST_DEFINE_00 was defined!Found in class2.cpp”)
#endif
int main(void){return 0;}
编译~
输出结果：
Compiling…
StdAfx.cpp
Compiling…
bitTest.cpp
class1.cpp
class2.cpp
DEF_TEST_DEFINE_11 was defined(after)! Found in class1.cpp!
Generating Code…
DEF_TEST_DEFINE_00 was defined!Found in class2.cpp
Linking…
defineTest.exe - 0 error(s), 0 warning(s)
仔细看一下，明白了吧？
Topics:
程序开发相关 |
Tags: #define, #pragma message, 作用域, 作用范围, 编程