[C语言 - 5] 预处理

1 //Like static constant
2 #define NUM 6
3 
4 //The truth of macro define is replacing the constant
5 //Replace "sum(a, b)" with "a+b"
6 #define sum(a, b) a+b

 1 #define NUM 1
 2 
 3 int main(int argc, const char * argv[]) {
 4 
 5 #if NUM == 0
 6     printf("0");
 7 #elif NUM > 0
 8     printf(">0");
 9 #elif NUM < 0
10     printf("<0");
11 #endif
12    
13     printf("\n");
14     return 0;
15 }