1 #include 
     
       2 #include 
      
        3 #include 
       
         4  5 int main() 6 { 7     //取整 8     printf("%ld\n",(long)19.999); 9     //保留0位小数部分10     printf("%.lf\n",19.999);11 12     //四舍五入13     //(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14     //所以一定要把数据和0.5用括号括起来，否则输出为015     printf("%ld\n",(long)(19.5+0.5));16     printf("%ld\n",(long)(19.49+0.5));17     printf("%ld\n",(long)(19.51+0.5));18 19     //整型用abs，实型用fabs20     printf("%ld\n",abs(-5));21     printf("%lf\n",fabs(-5.123));22     return 0;23 }