C library - EDOM Macro

The C library EDOM Macro represents a domain error, which occurs if an input argument is outside the domain, over which the mathematical function is defined and errno is set to EDOM.

The programmers can check errno after calling such functions to handle domain errors.

Syntax

Following is the C library syntax of the EDOM Macro −

#define EDOM some_value

Parameters

• The EDOM is known for macros. So, it does not accept any parameter.

Return Value

• This function does not return any value.

Example 1

Following is the C library program to see the illustration of EDOM Macro.

#include <stdio.h>
#include <errno.h>
#include <math.h>

int main () {
   double val;

   errno = 0;
   val = sqrt(-10);
   
   if(errno == EDOM) {
      printf("Invalid value \n");
   } else {
      printf("Valid value\n");
   }
   
   errno = 0;
   val = sqrt(10);
   
   if(errno == EDOM) {
      printf("Invalid value\n");
   } else {
      printf("Valid value\n");
   }
   
   return(0);
}

Output

On execution of above code, we get the following result −

Invalid value
Valid value

Example 2

In this program, we calculatethe arcsine of an input value using the function asin().

#include <stdio.h>
#include <math.h>
#include <errno.h>

int main() {
   double invalid_value = 2.0; 

   double result = asin(invalid_value);
   if (errno == EDOM) {
       printf("Arcsine of %f is not defined.\n", invalid_value);
   } else {
       printf("Arcsine of %f = %f radians\n", invalid_value, result);
   }

   return 0;
}

Output

After executing the above code, we get the following result −

Arcsine of 2.000000 is not defined.