c输出格式

 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>

 int main()
 {
     //取整
     printf("%ld\n",(long)19.999);
     //保留0位小数部分
     printf("%.lf\n",19.999);

     //四舍五入
     //(long)是取整最右边的数据，而数据与数据之间以运算符号分开
     //所以一定要把数据和0.5用括号括起来，否则输出为0
     printf("%ld\n",(long)(19.5+0.5));
     printf("%ld\n",(long)(19.49+0.5));
     printf("%ld\n",(long)(19.51+0.5));

     //整型用abs，实型用fabs
     printf("%ld\n",abs(-));
     printf("%lf\n",fabs(-5.123));
     return ;
 }