C語言宏定義小技巧

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正文

1

#define與#undef

 1#include?
 2#include?
 3
 4#define?HELLO_BUG???100
 5
 6int?main(int?argc,?char?*argv[])?{
 7
 8?printf("hello?bug?%d
",HELLO_BUG);
 9
10#undef?HELLO_BUG
11
12?printf("hello?bug?%d
",HELLO_BUG);
13?return?0;
14}

2

X-MACRO

1#define?X_MACRO(a,?b)???a 2//do?something 3#undef?X_MACRO 4 5#define?X_MACRO(a,?b)???b 6//do?something 7#undef?X_MACRO

 1/*************消息定義**********/
 2#define?MSG_TABLE??????????????????
 3????X_MACROS(USER_MSG1,?MsgProc1)??
 4????X_MACROS(USER_MSG2,?MsgProc2)??
 5????X_MACROS(USER_MSG3,?MsgProc3)??
 6
 7/*************消息枚舉定義**********/
 8typedef?enum?{
 9????#define?X_MACROS(a,?b)?a,
10????MSG_TABLE
11????#undef?X_MACROS
12????MSG_MAX?
13}?MSG_TYPE;
14
15/*************消息處理定義**********/
16const?Proc?Proc_table[]?=?{
17????#define?X_MACROS(a,?b)?b,
18????MSG_TABLE
19????#undef?X_MACROS?
20};
21
22/*************實際使用**********/
23void?sMessageProc(MSG_TYPE?msgtype)
24{
25????(Proc_table[msgtype])();
26}