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PHP is_bool() Function

Quick summary: The PHP is_bool() function checks whether a variable is of type boolean.

PHP is_bool() Syntax 

is_bool(mixed $value): bool
PHP

PHP is_bool() Basic examples 

var_dump(is_bool(true));
PHP
Output:
bool(true)

Returns true for boolean values.

var_dump(is_bool(0));
PHP
Output:
bool(false)

Integers are not booleans.

PHP is_bool() Real-world usage 

$flag = false;
if (is_bool($flag)) {
    echo 'Boolean flag';
}
PHP
Output:
Boolean flag

Validates strict boolean flags.

PHP is_bool() Edge cases 

var_dump(is_bool('true'));
PHP
Output:
bool(false)

Strings are not booleans.

PHP is_bool() Common mistakes

Confusing truthy values with booleans

Not all truthy values are booleans.

Incorrect
is_bool(1);
Correct
is_bool(true);

Use strict booleans when type matters.

PHP is_bool() Frequently Asked Questions

What does is_bool() do?

Checks if a variable is boolean.

Return type?

bool.

Use case?

Type validation.

Common mistake?

Confusing truthy values.

Handles strings?

No.

Strict?

Yes.

Alternative?

gettype().

Performance?

Fast.

Safe?

Yes.

Used in APIs?

Yes.

Handles null?

No.

Best practice?

Validate input types.

PHP is_bool() Related PHP Functions