PHP Variable Handling is_double() Function

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The PHP Variable Handling is_double() function is used to check if a value is a decimal number. It works the same as is_float(). It is available in PHP 4, 5, 7, and 8. It helps to check if a number has a decimal point. If the number is an integer it will return false. If the number is a float like 3.5, it will return true. It is useful in math and calculations.

Syntax

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

bool is_double (mixed $value)

Parameters

This function accepts $value parameter which takes one value to check. The value can be a number, variable or it can be an expression.

Return Value

The is_double() function returns TRUE if the value is a float (decimal number). And returns FALSE if the value is not a float.

PHP Version

First introduced in core PHP 4, the is_double() 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_double() function to check if a number is a float. It returns true for decimal numbers.

<?php
   // A decimal number
   $num = 4.5; 
   if (is_double($num)) {
      echo "$num is a float.";
   } else {
      echo "$num is not a float.";
   }
?>

Output

Here is the outcome of the following code −

4.5 is a float.

Example 2

In the below PHP code we will use the is_double() function and check an integer value. As integers are not floats so it will return false.

<?php
   // An integer
   $num = 10; 
   if (is_double($num)) {
      echo "$num is a float.";
   } else {
      echo "$num is not a float.";
   }
?> 

Output

This will generate the below output −

10 is not a float.

Example 3

Now the below code checks different values that they are decimal values or not using the is_double() function.

<?php
   var_dump(is_double(10.01));    
   var_dump(is_double('def'));    
   var_dump(is_double(33));       
   var_dump(is_double(33.8));     
   //Scientific Notation    
   var_dump(is_double(2e7));      
   var_dump(is_double(false));    
?>

Output

This will produce following result −

bool(true)
bool(false)
bool(false)
bool(true)
bool(true)
bool(false)

Example 4

In the following example, we are using the is_double() function to use an array and a loop to check multiple values. It prints that each value is a float or not.

<?php
   // Array with different types
   $values = [3.14, 7, "hello", 2.5]; 

   foreach ($values as $val) {
      if (is_double($val)) {
         echo "$val is a float.\n";
      } else {
         echo "$val is not a float.\n";
      }
   }
?> 

Output

Following is the output of the above code −

3.14 is a float.  
7 is not a float.  
hello is not a float.  
2.5 is a float.