isinf() — Determines if X is ± infinity

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 isinf(real-floating x);       

#define __STDC_WANT_DEC_FP__      
#include <math.h>

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

#define _TR1_C99      
#include <math.h>

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

General description

The isinf() macro or function template determines if its argument is plus or minus infinity.

Function	Hex	IEEE
isinf	X	X

Notes:

To use IEEE decimal floating-point, the hardware must have the Decimal Floating-Point Facility installed.
This function works in IEEE decimal floating-point format. See "IEEE Decimal Floating-Point" for more information.

Returned value

The isinf() macro returns 1 if the argument is plus or minus infinity, else returns 0. The C++ function template returns true if the argument is plus or minus infinity, else returns false.

Special behavior in hex: The isinf() macro returns zero. The C++ function template returns false.

Related information

math.h