Defined in header
float trunc( float arg );
double trunc( double arg );
long double trunc( long double arg );
double trunc( Integral arg );
|arg||-||floating point value|
 Return value
If no errors occur, the nearest integer value not greater in magnitude than
arg (in other words,
arg rounded towards zero), is returned.
 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.
argis ±∞, it is returned, unmodified
argis ±0, it is returned, unmodified
- If arg is NaN, NaN is returned
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 std::intmax_t), when stored in an integer variable.
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.
trunc(+2.7) = 2.000000 trunc(-2.9) = -2.000000 trunc(-0.0) = -0.000000 trunc(-Inf) = -inf
 See also
| nearest integer not greater than the given value |
| nearest integer not less than the given value |
| nearest integer, rounding away from zero in halfway cases |
C documentation for trunc