Floor
Defined in header <cmath>
.
Description
Computes the largest integer value not greater than num
.
The library provides overloads of std::floor for all cv-unqualified floating-point types as the type of the parameter num
(od C++23).
Additional Overloads are provided for all integer types, which are treated as double (od C++11).
Declarations
- C++23
- C++11
// 1)
constexpr /* floating-point-type */ floor( /* floating-point-type */ num );
// 2)
constexpr float floorf( float num );
// 3)
constexpr long double floorl( long double num );
// 4)
template< class Integer >
constexpr double floor ( Integer num );
// 1)
float floor ( float num );
// 2)
double floor ( double num );
//3)
long double floor ( long double num );
// 4)
float erfcf( float num );
// 5)
long double erfcl( long double num );
// 6)
template< class Integer >
double floor ( Integer num );
Parameters
num
- floating-point or integer value
Return value
If no errors occur, the largest integer value not greater than num
, that is ⌊num⌋, 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.
- If num is
±∞
, it is returned, unmodified - If num is
±0
, it is returned, unmodified - If num is NaN, NaN is returned
Notes
FE_INEXACT may be (but isn't required to be) raised when rounding 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 additional overloads are not required to be provided exactly as Additional Overloads.
They only need to be sufficient to ensure that for their argument num
of integer type,
std::floor(num)
has the same effect as std::floor(static_cast<double>(num))
Examples
#include <cmath>
#include <iostream>
int main()
{
std::cout
<< std::fixed
<< "floor(+2.7) = "
<< std::floor(+2.7) << '\n'
<< "floor(-2.7) = "
<< std::floor(-2.7) << '\n'
<< "floor(-0.0) = "
<< std::floor(-0.0) << '\n'
<< "floor(-Inf) = "
<< std::floor(-INFINITY) << '\n';
}
floor(+2.7) = 2.000000
floor(-2.7) = -3.000000
floor(-0.0) = -0.000000
floor(-Inf) = -inf