C in a Nutshell

Name

trunc

Synopsis

Rounds a floating-point number toward 0 to an integer value

#include <math.h>
doubletrunc( double x );
float truncf( float x );
long double truncl( long double x );

The trunc() functions round the value of their argument, x, to the nearest integer value whose magnitude is not greater than that of x—in other words, toward 0.

Example

printf("trunc(-1.7) = %.2f   trunc(1.4) = %.2f   trunc(1.5) = %.2f\n",
        trunc(-1.7),  trunc(1.4), trunc(1.5) );

printf("round(-1.7) = %.2f   round(1.4) = %.2f   round(1.5) = %.2f\n",
        round(-1.7), round(1.4), round(1.5) );

This code produces the following output:

trunc(-1.7) = -1.00   trunc(1.4) = 1.00   trunc(1.5) = 1.00
round(-1.7) = -2.00   round(1.4) = 1.00   round(1.5) = 2.00

See Also

rint(), lrint(), llrint(), round(), lround(), llround(), nearbyint()