C library - fegetexceptflag() function

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The C fenv library fegetexceptflag() function is used to retrieve the current state or full content of the floating-point exceptions flag specified by the 'excepts' argument. This argument is a bitwise OR combination of the floating-point exception macros, such as FE_DIVBYZERO, FE_INEXACT, FE_INVALID, FE_OVERFLOW, and FE_UNDERFLOW.

The full contents of a floating-point exception flag are not just a true/false indicating whether the exception is occurred. Instead, it may be more complex, such as a structure that includes both the status of the exception and additional details like the address of the code that caused the exception.

Syntax

Following is the C library syntax of fegetexceptflag() function −

int fegetexceptflag( fexcept_t* flagp, int excepts );

Parameters

This function accepts a following parameters −

• flagp − It represent a pointer to an 'fexcept_t' object where the flags will be stored or read from.

• excepts − It represent a bitmask listing of the exception flags to get.

Return Value

This function returns 0 if it successfully get the state of the specified exception, non-zero otherwise.

Example 1

Following is the basic C program to demonstrate the use of fegetexceptflag() function.

#include <stdio.h>
#include <fenv.h>

int main() {
   // Declare a variable to hold the exception flags
   fexcept_t flag;
   
   // Perform some floating-point operations that may raise exceptions
   double x = 1.0 / 0.0;
   
   // retrieve the state of the FE_DIVBYZERO exception flag
   if (fegetexceptflag(&flag, FE_DIVBYZERO) != 0) {
      printf("Failed to obtain the state of the FE_DIVBYZERO exception flag.\n");
      return 1;
   } else {
      printf("Successfully obtained the state of the FE_DIVBYZERO exception flag.\n");
   }
   return 0;
}

Output

Following is the output −

Successfully obtained the state of the FE_DIVBYZERO exception flag.

Example 2

The following C program uses the fegetexceptflag() function. Here, we obtaining multiple exception flags.

#include <stdio.h>
#include <fenv.h>
int main() {
   fexcept_t flag;
   
   // Perform some floating-point operations that may raise exceptions
   double x = 0.0 / 0.0;
   double y = 1e308 * 1e308;
   
   // Get the state of the FE_INVALID and FE_OVERFLOW exception flags
   if (fegetexceptflag(&flag, FE_INVALID | FE_OVERFLOW) != 0) {
      printf("Failed to obtain the state of the FE_INVALID and FE_OVERFLOW exception flags.\n");
      return 1;
   } else {
      printf("Successfully obtained the state of the FE_INVALID and FE_OVERFLOW exception flags.\n");
   }
   return 0;
}

Output

Following is the output −

Successfully obtained the state of the FE_INVALID and FE_OVERFLOW exception flags.

Example 3

The example below, returns 0 if it successfully get the state of the specified exception.

#include <stdio.h>
#include <fenv.h>
#include <math.h>
int main() {
   fexcept_t flag;

   // Perform some floating-point operations that may raise exceptions
   double x = 10.0 / 0.0;
   double square_root = sqrt(-1.0);

   // Get the state of the FE_INVALID and FE_OVERFLOW exception flags
   int res = fegetexceptflag(&flag, FE_INVALID | FE_OVERFLOW);
   printf("%d", res);
   return 0;
}

Output

Following is the output −

0