From cppreference.com
Defined in header
floatfloor(floatnum);doublefloor(doublenum);longdoublefloor(longdoublenum); (1)(until C++23)constexpr/*floating-point-type*/floor(/*floating-point-type*/num);(since C++23)floatfloorf(floatnum); (2)(since C++11)
(constexpr since C++23)longdoublefloorl(longdoublenum); (3)(since C++11)
(constexpr since C++23)
(since C++26)
Defined in header
template</*math-floating-point*/V>constexpr/*deduced-simd-t*/<V>floor(constV&v_num); (S) (since C++26)
(since C++11)
Defined in header
template<classInteger>doublefloor(Integernum); (A)(constexpr since C++23)1-3) 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.(since C++23)
A) Additional overloads are provided for all integer types, which are treated as double.
(since C++11)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.
Return value
num
Error handling
Errors are reported as specified in
.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
The current
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
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
), when stored in an integer variable.
The additional overloads are not required to be provided exactly as (A). 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)).
Example
Run this code
#include<cmath>#include<iostream>intmain(){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';}Output:
floor(+2.7) = 2.000000 floor(-2.7) = -3.000000 floor(-0.0) = -0.000000 floor(-Inf) = -inf See also