abs(), absf(), absl() — Calculate integer absolute value

Standards

Standards / Extensions	C or C++	Dependencies
ISO C POSIX.1 XPG4 XPG4.2 C99 Single UNIX Specification, Version 3 C/C++ DFP C++ TR1 C99	both

Format

#include <stdlib.h>

int abs(int n);
long abs(long n);                    /* C++ only */

#include <math.h>

double abs(double n);                /* C++ only */
float abs(float n);                  /* C++ only */
long double abs(long double n);      /* C++ only */
float absf(float n);
long double absl(long double n);

DFP:

#define __STDC_WANT_DEC_FP__
#include <math.h>

_Decimal32  abs(_Decimal32 x);   /* C++ only */
_Decimal64  abs(_Decimal64 x);   /* C++ only */
_Decimal128 abs(_Decimal128 x);  /* C++ only */

C++ TR1 C99:

#define _TR1_C99
#include <inttypes.h>
intmax_t abs(intmax_t n);  

#define _TR1_C99 
#include <stdlib.h>
long long abs(long long n);

General description

The functions abs(), absf(), and absl() return the absolute value of an argument n.

For the integer version of abs(), the minimum allowable integer is INT_MIN+1. (INT_MIN is a macro that is defined in the limits.h header file.) For example, with the z/OS® XL C/C++ compiler, INT_MIN+1 is -2147483648.

For the double, float, and long double versions of abs(), the minimum allowable values are DBL_MIN+1, FLT_MIN+1, and LDBL_MIN+1, respectively. (The floating-point macro constants are defined in the float.h header file.)

If the value entered cannot be represented as an integer, the abs(), absf(), and absl() functions return the same value.

Note: These functions work in both IEEE Binary Floating-Point and hexadecimal floating-point formats. See IEEE binary floating-point for more information about IEEE Binary Floating-Point.

Special behavior for C++: For C++ applications, abs() is also overloaded for the types long, float, and long double.

Returned value

The returned value is the absolute value, if the absolute value is possible to represent.

Otherwise the input value is returned.

There are no errno values defined.

Example

CELEBA02

⁄* CELEBA02                                      

   This example calculates the absolute value of an integer                     
   x and assigns it to y.                                                       
                                                                                
 *⁄                                                                             
#include <stdio.h>                                                              
#include <stdlib.h>                                                             
                                                                                
int main(void)                                                                  
{                                                                               
    int x = -4, y;                                                              
                                                                                
    y = abs(x);                                                                 
    printf("The absolute value of %d is %d.\n", x, y);                          
}

Output

The absolute value of    -4 is    4.