In this post, This function checks whether a variable is of type boolean or not.

1. Code:

  <?php
	function checkTheValueIsBoolean($var){
		return filter_var($var, FILTER_VALIDATE_BOOLEAN);
	} 
	var_dump(checkTheValueIsBoolean("off"));
	echo "<br>";
	var_dump(checkTheValueIsBoolean("on"));
?> 

2. Example:

Input:

input: "off"
Input: "on"
input: "a"

Output:

output: true
output: true
output: false