PHP Variable Handling is_integer() Function

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The PHP Variable Handling is_integer() function is used to checks that a number is an integer or not. It is a built-in function. It works in the same way as the is_int() method. This function accepts one value as input. If the value is an integer, it returns true. If the value is not an integer, it returns false. It is useful when you want to know if a number is a complete number. This method makes it easy to create error-free code. It works with a wide range of values.

Syntax

Below is the syntax of the PHP Variable Handling is_integer() function −

bool is_integer ( mixed $value )

Parameters

This function accepts $value parameter which contains the value to check for integers.

Return Value

The is_integer() function returns TRUE if the value is an integer. And it returns FALSE if the value is not an integer.

PHP Version

First introduced in core PHP 4, the is_integer() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

Here is the basic example of the PHP Variable Handling is_integer() function to check if a given number is an integer. It prints a message accordingly.

<?php
   // Define a number
   $num = 10; 
   if (is_integer($num)) {  
      echo "$num is an integer.";  
   } else {  
      echo "$num is not an integer.";  
   }  
?>

Output

Here is the outcome of the following code −

10 is an integer.

Example 2

In the below PHP code we will use the is_integer() function and check an integer inside a string. So we will store a number inside a string. Even though "25" looks like an integer, it is a string, so the function will return false.

<?php
// Define a number inside a string
$num = "25"; 
if (is_integer($num)) {  
    echo "$num is an integer.";  
} else {  
    echo "$num is not an integer.";  
}
?> 

Output

This will generate the below output −

25 is not an integer.

Example 3

Following example shows the return values with different types of variables using the is_integer() function.

<?php
   $a = 33;
   echo "a is "; var_dump(is_integer($a)); 

   $b = "33";
   echo "b is "; var_dump(is_integer($b)); 

   $c = 33.5;
   echo "c is "; var_dump(is_integer($c)); 

   $d = "33.5";
   echo "d is "; var_dump(is_integer($d)); 

   $e = true;
   echo "e is "; var_dump(is_integer($e)); 

   $f = false;
   echo "f is "; var_dump(is_integer($f)); 

   $g = null;
   echo "g is "; var_dump(is_integer($g)); 
?> 

Output

This will create the below output −

a is bool(true)
b is bool(false)
c is bool(false)
d is bool(false)
e is bool(false)
f is bool(false)
g is bool(false)