isfinite() — Determines if its argument has a finite value

Standards

Standards / Extensions C or C++ Dependencies
C99
Single UNIX Specification, Version 3
C/C++ DFP
C++ TR1 C99
both
z/OS® V1R8

Format

#define _ISOC99_SOURCE
#include <math.h>

int isfinite(real-floating x);

#define __STDC_WANT_DEC_FP__
#include <math.h>

int isfinite(real-floating x);  /* C only */
int isfinite(decimal-floating x);  /*C only */
bool isfinite(real-floating x);  /* C++ only */

#define _TR1_C99
#include <math.h>

bool isfinite(real-floating x);  /* C++ only */

General description

The isfinite() macro or function template determines if its argument has a finite value.

Function Hex IEEE
isfinite X X
Notes:
  1. To use IEEE decimal floating-point, the hardware must have the Decimal Floating-Point Facility installed.
  2. This function works in IEEE decimal floating-point format. See "IEEE Decimal Floating-Point" for more information.

Returned value

The isfinite() macro returns 1 if and only if its argument value is finite, else returns 0. The C++ function template returns true if and only if its argument value is finite, else returns false.

Special behavior in hex: The isfinite() macro always returns 1. The C++ function template always returns true.

Related information