Rounds a real number down to an integer value

#include <math.h>
double floor ( double x  );
float floorf ( float x  );         (C99)
long double floorl ( long double x  );         (C99)

The floor( ) function returns the greatest integer that is less than or equal to its argument. However, the function does not have an integer type; it returns an integer value, but with a floating-point type.

Example

/* Scale a point by independent x and y factors */
struct point { int x, y; };

int width_orig = 1024, height_orig = 768;
int width_new = 800, height_new = 600;

struct point scale( struct point orig )
{
  struct point new;
  new.x = (int)floor( orig.x * (double)width_new  / (double)width_orig  );
  new.y = (int)floor( orig.y * (double)height_new / (double)height_orig );
  return new;
}

See Also

ceil( ), round( ); the C99 rounding functions that return floating-point types: trunc( ), rint( ), nearbyint( ), nextafter( ), and nexttoward( ); the C99 rounding functions that return integer types: lrint( ), lround( ), llrint( ), and llround( ); the fesetround( ) and fegetround( ) functions, which operate on the C99 floating-point environment.