PHP Variable Handling is_int() Function

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The PHP Variable Handling is_int() function is used to check if a variable is an integer. It supports PHP 4, PHP 5, PHP 7, and PHP 8. An integer is a whole number, like 10, -5 or 1000. If the variable is an integer, the function will return "true." If the variable isn't an integer, it returns false.

This function is useful for determining whether a given number is an integer. If we want to know whether a value is a number (including numeric strings), we can use is_numeric. This function helps to create error-free and dependable code.

Syntax

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

bool is_int ( mixed $value )

Parameters

This function accepts $value parameter which is the variable that we want to check.

Return Value

The is_int() function returns TRUE if the variable is an integer. It returns FALSE if the variable is not an integer.

PHP Version

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

Example 1

In this simple example we will show the usage of the PHP Variable Handling is_int() function. We will check if the variable $value is an integer. If it is, we will output the message "The value is an integer". Otherwise, we will print the message "The value is not an integer".

<?php
   // Assign an integer to the variable
   $value = 10; 
   // Check if value is an integer
   if (is_int($value)) { 
      echo "The value is an integer.";
   } else {
      echo "The value is not an integer.";
   }
?>

Output

Here is the outcome of the following code −

The value is an integer.

Example 2

In the below PHP code we will use the is_int() function and check if a string 20 is considered an integer. Even though the string looks like an integer the function is_int() will return false because it is not an actual integer.

<?php
   // Assign a string to the variable
   $value = "20"; 
   // Check if value is an integer
   if (is_int($value)) { 
      echo "The value is an integer.";
   } else {
      echo "The value is not an integer.";
   }
?> 

Output

This will generate the below output −

The value is not an integer.

Example 3

Now the below code retrieves specific information from is_int(), and prints it.

<?php
   // A string from user input 
   $value = "25"; 
   // Check if value is a number (numeric string)
   if (is_numeric($value)) { 
      // Convert to integer and check 
      if (is_int($value + 0)) { 
         echo "The value is an integer.";
      } else {
         echo "The value is a numeric string, not an integer.";
      }
   } else {
      echo "The value is not numeric.";
   }
?> 

Output

This will create the below output −

The value is an integer.

Example 4

Following example demonstrates return values with different types of variables −

<?php
   $a = 33;
   echo "a is "; var_dump(is_int($a)); echo "\n";

   $b = "33";
   echo "b is "; var_dump(is_int($b)); echo "\n";

   $c = 33.5;
   echo "c is "; var_dump(is_int($c)); echo "\n";

   $d = "33.5";
   echo "d is "; var_dump(is_int($d)); echo "\n";

   $e = true;
   echo "e is "; var_dump(is_int($e)); echo "\n";

   $f = false;
   echo "f is "; var_dump(is_int($f)); echo "\n";

   $g = null;
   echo "g is "; var_dump(is_int($g)); echo "\n";
?>

Output

This will produce following result −

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)