Round up a value to the next integer
#include <math.h> double ceil( double x ); float ceilf( float x ); long double ceill( long double x );
The ceil(), ceilf(), and ceill() functions round the value of x up to the next integer (rounding towards the ceiling).
To check for error situations, use feclearexcept() and fetestexcept(). For example:
The smallest integer ≥ x with the same sign as x.
If x is: | These functions return: | Errors: |
---|---|---|
±0.0 | x | — |
±Inf | x | — |
NaN | NaN | — |
These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.
#include <stdio.h> #include <math.h> #include <stdlib.h> int main( void ) { printf( "%f %f %f %f %f\n", ceil( -2.1 ), ceil( -2. ), ceil( 0.0 ), ceil( 2. ), ceil( 2.1 ) ); return EXIT_SUCCESS; }
produces the output:
-2.000000 -2.000000 0.000000 2.000000 3.000000
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |