std::abs(float),std::fabs,std::fabsf,std::fabsl(3)

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

Synopsis
   Defined in header <cmath>
   Defined in header <cstdlib>
   float abs( float arg ); (1) (constexpr since C++23)
   double abs( double arg ); (2) (constexpr since C++23)
   long double abs( long double arg ); (3) (constexpr since C++23)
   Defined in header <cmath>
   float fabs ( float arg ); (4) (constexpr since C++23)
   float fabsf( float arg ); (5) (since C++11)
                        (constexpr since C++23)
   double fabs ( double arg ); (6) (constexpr since C++23)
   long double fabs ( long double arg ); (7) (constexpr since C++23)
   long double fabsl( long double arg ); (8) (since C++11)
                        (constexpr since C++23)
   double fabs ( IntegralType arg ); (9) (since C++11)
                        (constexpr since C++23)
   1-8) Computes the absolute value of a floating point value arg.
   9) A set of overloads or a function template accepting an argument of any integral
   type. Equivalent to (6) (the argument is cast to double).
   For integral arguments, the integral overloads of std::abs are likely better
   matches. If std::abs is called with an unsigned integral argument that cannot be
   converted to int by integral promotion, the program is ill-formed.

Parameters
   arg - Value of a floating-point or integral type

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

Error handling
   This function is not subject to any of the error conditions specified in
   math_errhandling.
   If the implementation supports IEEE floating-point arithmetic (IEC 60559),
     * If the argument is ±0, +0 is returned
     * If the argument is ±∞, +∞ is returned
     * If the argument is NaN, NaN is returned

Example
// Run this code
 #include <iostream>
 #include <cmath>
 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';
 }

Possible output:
 abs(+3.0) = 3
 abs(-3.0) = 3
 abs(-0.0) = 0
 abs(-Inf) = inf
 abs(-NaN) = nan
  Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
                       overloads of std::abs were declared these overloads in
   LWG 2192 C++98 inconsistently both headers
                       declared in two headers
                       overloads of std::abs for integer
   LWG 2735 C++11 types removed the requirement
                       returning double was erroneously
                       required

See also
   abs(int)
   labs computes absolute value of an integral value (\(\small{|x|}\)|x|)
   llabs (function)
   (C++11)
   copysign
   copysignf
   copysignl copies the sign of a floating point value
   (C++11) (function)
   (C++11)
   (C++11)
   signbit checks if the given number is negative
   (C++11) (function)
   abs(std::complex) returns the magnitude of a complex number
                      (function template)
   abs(std::valarray) applies the function abs to each element of valarray
                      (function template)