php.is_bool()

Variable evaluation refers to the method of determining whether a given PHP variable is a specific type or within a given string or expression.

Variable evaluation is a fantastic feature is it can allow you to quickly process and evaluate whether a given user input is a specific type or not. This can help you sanitize user data and prevent malicious content from passing through.

In this tutorial, we will cover one of the fundamental methods in PHP to determine whether a given variable is a Boolean value or not.

PHP is_bool() Function

As the name suggests, the is_bool() method allows to determine whether a given input is a Boolean Value or not.

The function syntax is as shown below:

is_bool(mixed $value): bool

The function accepts only one parameter:

1. value - this refers to the value whose type you wish to evaluate.

The function returns a Boolean True is the input is bool type and False if otherwise.

Examples

The following example demonstrates how to use the is_bool() method to check if a given variable is a Boolean Type.

$my_var = true;
if (is_bool($my_var)) {
  echo "The variable is a boolean value.";
} else {
  echo "The variable is not a boolean value.";
}

Output:

The variable is a boolean value.

Example 2

We can also use the is_bool() method to check if the return value of a given function is a boolean as demonstrated in the snippet below:

function is_active($user) {
  // some code to check if the user is active
  return true;
}

if (is_bool(is_active("Peter"))) {
  echo "The function returned a boolean value.";
} else {
  echo "The function did not return a boolean value.";
}

Output:

The function returned a boolean value.

Example 3

We can also use the is_bool() method to validate user input as demonstrated in the code below:

$user_input = "true";

if (is_bool($user_input)) {
  echo "The input is a boolean value.";
} else {
  echo "The input is not a boolean value.";
}

Resulting output:

The input is not a boolean value.

In this case, the is_bool() function returns false asthe value of $user_input is a string, not a boolean value.

Conclusion

In this post, we discussed how to work with the is_bool() function to perform a variety of tasks. For example, we discussed to validate a function return value. We also used it to validate the user input.