How to check if a variable is a Boolean in PHP?
Boolean variables contain true or false values. To find out if any variable contains a Boolean value, different approaches can be used:
- is_bool($var): The function is_bool() checks whether a variable’s type is Boolean and returns true or false.
- Comparison using “===” or ($var===true || $var===false): If you compare the variable with the operator “===” with true and false and if it is identical to one of the values, then it is a boolean value. Since the functionality of is_bool($var) is same, the function should be preferred.
- Comparison using “==” or ($var == true || $var == false): If you use “==” as an operator instead, the test is more tolerant. For example, 0(integer) or “”(empty string) would also result in a Boolean value.
- gettype($var): If you apply gettype() to a variable, you will get the datatype of the variable as a string. This can be evaluated. In case of boolean variables it must have the value “boolean”.
The recommended way to check the variables is to use is_bool(). It is readable for other developers and is performant at the same time.
Example 1: is_bool($var)
<?php
function myFunction($bool)
{
if (!is_bool($bool))
{
throw new Exception('Function myFunction expects a Boolean value.');
}
echo("myFunction called successfully.\n");
}
try
{
myFunction(false);
myFunction(true);
myFunction(0);
}
catch (Exception $e)
{
echo('Error with message "'.$e->getMessage().'" in line '.$e->getLine().'.');
}
?>
Output:
myFunction called successfully. myFunction called successfully. Error with message "Function myFunction expects a Boolean value." in line 6.
Example 2: Comparison using “===”
<?php
function myFunction($bool)
{
if ($bool!==true && $bool!==false)
{
throw new Exception('Function myFunction expects a Boolean value.');
}
echo("myFunction called successfully.\n");
}
try
{
myFunction(false);
myFunction(true);
myFunction(0);
}
catch (Exception $e)
{
echo('Error with message "'.$e->getMessage().'" in line '.$e->getLine().'.');
}
?>
Output:
myFunction called successfully. myFunction called successfully. Error with message "Function myFunction expects a Boolean value." in line 6.
Example 3: Comparison using “==”
<?php
function myFunction($bool)
{
if ($bool!=true && $bool!=false)
{
throw new Exception('Function myFunction expects a Boolean value.');
}
echo("myFunction called successfully.\n");
}
try
{
myFunction(false);
myFunction(true);
myFunction(0);
}
catch (Exception $e)
{
echo('Error with message "'.$e->getMessage().'" in line '.$e->getLine().'.');
}
?>
Output:
myFunction called successfully. myFunction called successfully. myFunction called successfully.
Example 4: Using gettype()
<?php
function myFunction($bool)
{
if (gettype($bool) !== 'boolean')
{
throw new Exception('Function myFunction expects a Boolean value.');
}
echo("myFunction called successfully.\n");
}
try
{
myFunction(false);
myFunction(true);
myFunction(0);
}
catch (Exception $e)
{
echo('Error with message "'.$e->getMessage().'" in line '.$e->getLine().'.');
}
?>
Output:
myFunction called successfully. myFunction called successfully. Error with message "Function myFunction expects a Boolean value." in line 6.
- Factorial Program in PHP Using Recursive Function
- Factorial in PHP Using For Loop
- How to Generate Random String in PHP
- Warning: Cannot modify header information – headers already sent
- How to send mail from localhost in PHP using WAMP server
- How to send mail from localhost in PHP using XAMPP
- How to Send an Email in PHP
- How to Validate an Email Address in PHP
- How to Check Format of Date in PHP
- How to check if a URL is valid in PHP
- How to Check Website Availability with PHP
- How to Generate Random Numbers in PHP
- How to Calculate Age from Date of Birth in PHP
- How to Extract Content Between HTML Tags in PHP
- How to check if file exists on remote server PHP
- How to get the client IP address in PHP
- How to Get IP Address of Server in PHP
- How to declare a global variable in PHP
- How to refresh a page with PHP
- How to get first day of week in PHP
- How to Change Max Size of File Upload in PHP
- How to compare two dates in PHP
- How to open a PDF file in browser with PHP
- How to Download file from URL using PHP
- How to remove an array element based on key in PHP
- How to get random value from an array in PHP
- How to calculate sum of an array in PHP
- How to remove null or empty values from an array in PHP
- How to Populate Dropdown List using Array in PHP
- How to get all the keys of an associative array in PHP
- How to get a value from an array in PHP
- How to remove a specific element from an array in PHP
- How to sort an associative array by value in PHP
- How to sort an associative array by key in PHP
- How to Check If a String Contains a Specific Word in PHP
- How to get the current date and time in PHP
- How to redirect to another page in PHP
- How to remove all spaces from a string in PHP
- Convert a date DD-MM-YYYY to YYYY-MM-DD in PHP
- Convert a date YYYY-MM-DD to DD-MM-YYYY in PHP
- How to get the current year in PHP
- How to convert a string to an integer in PHP
- How to get the first element of an array in PHP
- How to convert date to timestamp in PHP
- PHP: Compare two arrays and get the difference
- How to remove duplicates from an array in PHP
- How to sort an array in alphabetical order in PHP
- How to merge multiple arrays into one array in PHP
- How to add an element to the end of an array in PHP
- How to add an element to the beginning of an array in PHP
- How to remove the last element from an array in PHP
- How to remove the first element from an array in PHP
- How to replace part of a string in PHP
- How to count repeated words in a string in PHP
- PHP – Count Array Elements
- How to Reverse an Array in PHP
- How to check if a value exists in an array in PHP
- How to check if a key exists in an array in PHP
- How to reverse a string in PHP
- How to check if a variable is null in PHP
- How to check if a variable is empty in PHP
- How to check if a variable is undefined in PHP
- Convert HTML entities back to characters – PHP
- How to find the length of a string in PHP
- How to capitalize the first letter of a string in PHP
- PHP – Uppercase the first letter of each word in a string
- How to convert a string to lowercase in PHP
- How to compare two strings in PHP
- How to get the URL of the current page in PHP
- How to convert a string into an array in PHP
- How to extract a substring from a string in PHP
- How to count number of words in a string in PHP
- How to remove special characters from a string in PHP
- How to replace a word in a string in PHP
- How to Concatenate Two Strings in PHP
- How to count the number of characters in a string in PHP
- PHP – Remove spaces at the beginning and end of a string
- How to filter an array by value in PHP
- PHP – Get Domain Name from URL
- How to create a log file in PHP
- How to add days to a date in PHP
- PHP – Get file extension
- How to save an image from a URL in PHP
- How to Edit PHP ini File in Ubuntu Terminal
- How to increase the execution time of a PHP script
- How to enable cURL in PHP WAMP, XAMPP, and Ubuntu
- Convert Array to JSON in PHP
- PHP – Read JSON file
- How to display HTML tags as plain text using PHP
- PHP – Create JSON file
- How to convert result of MySQL query in JSON format
- PHP – Read CSV File into an Array
- How to convert an object to associative array in PHP
- How to extract or unzip a folder on FTP server in PHP
- How to Import CSV File in MySQL PHP
- Get Data From a Database Without Refreshing the Browser Using Ajax
- How to connect to Oracle database with PHP
- Connect to a PostgreSQL database with PHP PDO
- PHP – Convert Multidimensional Array to XML file
- What is PHP and how can I learn it?
- Hello World in PHP
- Comments in PHP
- How to Define a Variable in PHP
- PHP global variable with Example
- PHP Variable Scope
- PHP – Static Variables
- Type casting in PHP
- PHP Type Juggling
- Variable variables in PHP
- How to echo an array in PHP?
- How to Convert Decimal to Binary in PHP?
- How to Convert Binary to Decimal in PHP?
- How to assign multiple variables at once in PHP
- How to extract $_GET / $_POST parameters in PHP
- How to use $_GET in PHP?
- How to get a variable name as a string in PHP?
- How to print all defined variables and values in PHP
- PHP References: When to Use Them, and How They Work
- List of Superglobal Variables in PHP
- How to return a variable by name from a function in PHP
- How to delete a variable in PHP
- What is the difference between == and === in PHP
- How to check if a variable is NULL in PHP?
- How to check if an object is an instance of a specific class in PHP?
- How to check if a variable is a Boolean in PHP?
- How to check if a variable is a String in PHP?
- How to check if a variable is an Integer in PHP?
- How to check if a variable is a float in PHP?
- How to check if a variable is an array in PHP?
- How to check if a variable is undefined in PHP?
- How do you determine the data type of a variable in PHP?
- Difference between Include and Require in PHP
- How to combine HTML and PHP?
- How to add a new line within echo in PHP?
- How to display PHP variable values with echo, print_r, and var_dump
- The 6 best PHP frameworks in 2021
- PHP MCQ – Multiple Choice Questions and Answers – Basics – Part 1
- PHP MCQ – Multiple Choice Questions and Answers – Basics – Part 2
- PHP MCQ – Multiple Choice Questions and Answers – Basics – Part 3
- PHP Questions and Answers – Functions – Part 1
- PHP Questions and Answers – Functions – Part 2
- PHP Questions and Answers – Arrays – Part 1
- PHP Questions and Answers – Arrays – Part 2
- PHP Questions and Answers – Arrays – Part 3
- PHP Questions and Answers – Arrays – Part 4
- PHP Questions and Answers – Object-Oriented OOP – Part 1
- PHP Questions and Answers – Object-Oriented OOP – Part 2
- PHP Questions and Answers – Object-Oriented OOP – Part 3
- PHP Questions and Answers – String – Part 1
- PHP Questions and Answers – String – Part 2
- PHP Questions and Answers – Regular Expressions
- PHP Questions and Answers – Exception Handling
