std::abs(float), std::fabs, std::fabsf, std::fabsl

Since C++23

Header: <cmath>

1-4) Computes the absolute value of the floating-point value num.The library provides overloads of std::abs and std::fabs for all cv-unqualified floating-point types as the type of the parameter num.(since C++23)

# Declarations

float abs( float num );
double abs( double num );
long double abs( long double num );

(until C++23)

constexpr /* floating-point-type */
abs( /* floating-point-type */ num );

(since C++23)

float fabs ( float num );
double fabs ( double num );
long double fabs ( long double num );

(until C++23)

constexpr /* floating-point-type */
fabs ( /* floating-point-type */ num );

(since C++23)

float fabsf( float num );

(since C++11) (constexpr since C++23)

long double fabsl( long double num );

(since C++11) (constexpr since C++23)

Additional overloads (since C++11)

template< class Integer >
double fabs ( Integer num );

(since C++11) (constexpr since C++23)

# Parameters

num: floating-point or integer value

# Return value

If successful, returns the absolute value of arg (|arg|). The value returned is exact and does not depend on any rounding modes.

# Notes

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::fabs(num) has the same effect as std::fabs(static_cast(num)).

# Example

#include <cmath>
#include <iostream>
 
int main()
{
    std::cout << "abs(+3.0) = " << std::abs(+3.0) << '\n'
              << "abs(-3.0) = " << std::abs(-3.0) << '\n';
 
    // special values
    std::cout << "abs(-0.0) = " << std::abs(-0.0) << '\n'
              << "abs(-Inf) = " << std::abs(-INFINITY) << '\n'
              << "abs(-NaN) = " << std::abs(-NAN) << '\n';
}

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
LWG 2192	C++98	overloads of std::abs wereinconsistently declared in two headers	declared these overloadsin both headers
LWG 2735	C++11	overloads of std::abs for integer typesreturning double was erroneously required	removed the requirement

std::abs(float), std::fabs, std::fabsf, std::fabsl

# Declarations

# Parameters

# Return value

# Notes

# Example

# Defect reports

# See also