C语言中宏的使用

不念不忘少年蓝@ 2022-08-10 16:39 204阅读 0赞

C语言中宏的使用（\#，\#\#，do…while(0)宏）

1.预定义宏的使用\_\_FILE\_\_，\_\_FUNCTION\_\_，\_\_LINE\_\_。

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1.  \#include <stdio.h> 
2.  void fun(void) 
3.  \{ 
4.   char v1; 
5.   short v2; 
6.   int v3; 
7.   long v4; 
8.   printf("v1: %x\\n",&v1); 
9.   printf("v2: %x\\n",&v2); 
10.  printf("v3: %x\\n",&v3); 
11.  printf("v4: %x\\n",&v4); 
12.  printf("file is :%s,\\tfunction is: %s,\\tline is :%d\\n",\_\_FILE\_\_,\_\_FUNCTION\_\_,\_\_LINE\_\_); 
13. \} 
14. 
15. int main() 
16. \{ 
17.  fun(); 
18.  printf("file is :%s,\\tfunction is: %s,\\tline is :%d\\n",\_\_FILE\_\_,\_\_FUNCTION\_\_,\_\_LINE\_\_); 
19.  return 0; 
20. \}

2.\#宏字符串化

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1.  \#include<stdio.h> 
2.  \#define dprintf(expr) printf("<main>%s=%d\\n",\#expr,expr) 
3.  int main() 
4.  \{ 
5.   int x=100; 
6.   int y=2; 
7.  
8.   dprintf(x/y);//\#expr相当于x/y expr是x/y的运算结果 \#是字符串化操作 
9.   dprintf(x+y); 
10.  dprintf(x+y+2); 
11.  return 0; 
12. \}

3.\#\#连接字符串

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1.  \#include<stdio.h> 
2.  \#define test(x) test \#\#x 
3.  void test1(int a) 
4.  \{ 
5.   printf("Test 1 integer: %d \\n",a); 
6.  \} 
7.  void test2(char \*s) 
8.  \{ 
9.   printf("Test 2 String: %s \\n",s); 
10. \} 
11. int main () 
12. \{ 
13.  test(1)(100); //test(1)等价于test； test\#\#1等价于test1；\#\#连接字符 
14.  test(2)("hello"); 
15.  return 0; 
16. \}

4.do...while(0)宏

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1.  \#include<stdio.h> 
2.  \#define hello(str) do\{\\ 
3.   printf("Hello:%s\\n",str);\\ 
4.   \}while(0) 
5.  
6.  int main() 
7.  \{ 
8.   int m=0; 
9.   if(m) 
10.  \{ 
11. 
12.  hello("hello true"); 
13. \} 
14.  else 
15.  hello("hello false"); 
16.  system("pause"); 
17.  return 0; 
18. \} 
19.

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