ANSI C标准中有几个标准预定义宏(也是常用的):
- LINE:在源代码中插入当前源代码行号;
- FILE:在源文件中插入当前源文件名;
- DATE:在源文件中插入当前的编译日期
- TIME:在源文件中插入当前编译时间
- STDC:当要求程序严格遵循ANSI C标准时该标识被赋值为1;
- __cplusplus:当编写C++程序时该标识符被定义。
#include <stdio.h>
int main(void) {
int answer;
short x = 1;
long y = 2;
float u = 3.0;
double v = 4.4;
long double w = 5.54;
char c = 'p';;
// __DATE__, __TIME__, __FILE__, __LINE__ 为预定义宏
printf("Date : %s\n", __DATE__);
printf("Time : %s\n", __TIME__);
printf("File : %s\n", __FILE__);
printf("Line : %d\n", __LINE__);
printf("Enter 1 or 0 : ");
scanf("%d", &answer);
// 这是一个条件表达式
printf("%s\n", answer?"You sayd YES":"You said NO");
// 各种数据类型的长度
printf("The size of int %d\n", sizeof(answer));
printf("The size of short %d\n", sizeof(x));
printf("The size of long %d\n", sizeof(y));
printf("The size of float %d\n", sizeof(u));
printf("The size of double %d\n", sizeof(v));
printf("The size of long double %d\n", sizeof(w));
printf("The size of char %d\n", sizeof(c));
}