assert Checks an assertion &reftitle.description; boolassert mixedassertion Throwablestringnulldescription&null; assert allows for the definition of expectations: assertions that take effect in development and testing environments, but are optimised away to have zero cost in production. Assertions should be used as a debugging feature only. One use case for them is to act as sanity-checks for preconditions that should always be &true; and that if they aren't upheld this indicates some programming errors. Another use case is to ensure the presence of certain features like extension functions or certain system limits and features. As assertions can be configured to be eliminated, they should not be used for normal runtime operations like input parameter checks. As a rule of thumb code should behave as expected even if assertion checking is deactivated. assert will check that the expectation given in assertion holds. If not, and thus the result is &false;, it will take the appropriate action depending on how assert was configured. The behaviour of assert is dictated by the following INI settings: &Name; &Default; &Description; &Changelog; zend.assertions 1 1: generate and execute code (development mode) 0: generate code but jump around it at runtime -1: do not generate code (production mode) assert.active &true; If &false;, assert does not check the expectation and returns &true;, unconditionally. Deprecated as of PHP 8.3.0. assert.callback &null; A user defined function to call when an assertion fails. It's signature should be: voidassert_callback stringfile intline nullassertion stringdescription Prior to PHP 8.0.0, the signature of the callback should be: voidassert_callback stringfile intline stringassertion stringdescription Deprecated as of PHP 8.3.0. assert.exception &true; If &true; will throw an AssertionError if the expectation isn't upheld. Deprecated as of PHP 8.3.0. assert.bail &false; If &true; will abort execution of the PHP script if the expectation isn't upheld. Deprecated as of PHP 8.3.0. assert.warning &true; If &true;, will emit an E_WARNING if the expectation isn't upheld. This INI setting is ineffective if assert.exception is enabled. Deprecated as of PHP 8.3.0. &reftitle.parameters; assertion This is any expression that returns a value, which will be executed and the result is used to indicate whether the assertion succeeded or failed. Prior to PHP 8.0.0, if assertion was a string it was interpreted as PHP code and executed via eval. This string would be passed to the callback as the third argument. This behaviour was DEPRECATED in PHP 7.2.0, and REMOVED in PHP 8.0.0. description If description is an instance of Throwable, it will be thrown only if the assertion is executed and fails. As of PHP 8.0.0, this is done prior to calling the potentially defined assertion callback. As of PHP 8.0.0, the &object; will be thrown regardless of the configuration of assert.exception. As of PHP 8.0.0, the assert.bail setting has no effect in this case. If description is a &string; this message will be used if an exception or a warning is emitted. An optional description that will be included in the failure message if the assertion fails. If description is omitted. A default description equal to the source code for the invocation of assert is created at compile time. &reftitle.returnvalues; assert will always return &true; if at least one of the following is true: zend.assertions=0 zend.assertions=-1 assert.exception=1 assert.bail=1 A custom exception object is passed to description. If none of the conditions are true assert will return &true; if assertion is truthy and &false; otherwise. &reftitle.changelog; &Version; &Description; 8.3.0 All assert. INI settings have been deprecated. 8.0.0 assert will no longer evaluate string arguments, instead they will be treated like any other argument. assert($a == $b) should be used instead of assert('$a == $b'). The assert.quiet_eval &php.ini; directive and the ASSERT_QUIET_EVAL constant have also been removed, as they would no longer have any effect. 8.0.0 If description is an instance of Throwable, the object is thrown if the assertion fails, regardless of the value of assert.exception. 8.0.0 If description is an instance of Throwable, no user callback is called even if it set. 8.0.0 Declaring a function called assert() inside a namespace is no longer allowed, and issues E_COMPILE_ERROR. 7.3.0 Declaring a function called assert() inside a namespace became deprecated. Such declaration now emits an E_DEPRECATED. 7.2.0 Usage of a string as the assertion became deprecated. It now emits an E_DEPRECATED notice when both assert.active and zend.assertions are set to 1. &reftitle.examples; 2); echo 'Hi!'; ]]> If assertions are enabled (zend.assertions=1) the above example will output: 2) in example.php:2 Stack trace: #0 example.php(2): assert(false, 'assert(1 > 2)') #1 {main} thrown in example.php on line 2 ]]> If assertions are disabled (zend.assertions=0 or zend.assertions=-1) the above example will output: 2, "Expected one to be greater than two"); echo 'Hi!'; ]]> If assertions are enabled the above example will output: If assertions are disabled the above example will output: 2, new ArithmeticAssertionError("Expected one to be greater than two")); echo 'Hi!'; ]]> If assertions are enabled the above example will output: If assertions are disabled the above example will output: &reftitle.seealso; assert_options