What is the usage of the assert function in PHP?

The assert function is used to check if a condition is true, and if it is false, it triggers an AssertionError exception. Its syntax is as follows:

assert ( $condition, $message )

The condition to be checked is stored in $condition, and an optional error message is stored in $message. If the condition is false, an AssertionError exception will be triggered and the error message (if provided) will be displayed. If the condition is true, nothing will happen.

The assert function is very useful for debugging code, as it can help quickly identify and fix issues. However, in a production environment, the assert function should be turned off to avoid performance loss.