double floor(double);

rounding down a number

compile in linux with: gcc floor.c -o floor -lm -Wall

#include <stdio.h> /* including standard library */
//#include <windows.h> /* uncomment this for Windows */
 
#include <math.h> /* including math library */
 
int main ( void ) 
{
double y,x;
x = 4.2;
y = 9.9;
printf("floor of %f is %f\n", x, floor(x) );
printf("floor of %f is %f\n ",y , floor(y) );
return 0;
}

 output:
 user@host:~$ ./floor 
 floor of 4.200000 is 4.000000
 floor of 9.900000 is 9.000000