trunc, truncf, truncl

Parameters

Return value

If no errors occur, the nearest integer value not greater in magnitude than arg (in other words, arg

Return value

Argument

Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559):

• The current rounding mode has no effect.
• If arg is ±∞, it is returned, unmodified.
• If arg is ±0, it is returned, unmodified.
• If arg is NaN, NaN is returned.

Notes

FE_INEXACT may be (but isn't required to be) raised when truncating a non-integer finite value.

The largest representable floating-point values are exact integers in all standard floating-point formats, so this function never overflows on its own; however the result may overflow any integer type (including intmax_t

The implicit conversion from floating-point to integral types also rounds towards zero, but is limited to the values that can be represented by the target type.

Example

#include <math.h>
#include <stdio.h>
 
int main(void)
{
    printf("trunc(+2.7) = %+.1f\n", trunc(+2.7));
    printf("trunc(-2.7) = %+.1f\n", trunc(-2.7));
    printf("trunc(-0.0) = %+.1f\n", trunc(-0.0));
    printf("trunc(-Inf) = %+f\n",   trunc(-INFINITY));
}

trunc(+2.7) = +2.0
trunc(-2.7) = -2.0
trunc(-0.0) = -0.0
trunc(-Inf) = -inf

References

See also