C/math.h/llrint
llrint: returns the value of arg rounded to the nearest long long integer
//Declaration: long long int llrintf(float arg);
long long int llrint(double arg);
long long int llrintl(long double arg);
#include <math.h>
#include <stdio.h>
int main(void)
{
printf("%l", llrintl (111111111111111.2));
return 0;
}