Definition
A definition is the description of a particular constant, function, method, property, class, trait, interface or enum.
A variable also has a definition, also called an initialisation: variables have no formal definition. They use an unconditional assignation to do so.
The definition is also called a declaration. The declaration must happen before usage.
Definitions happens in custom code, in libraries or in extensions.
There are functions dedicated to listing defined elements: get_declared_constants(), get_declared_traits(), get_declared_interfaces(), get_declared_classes(), get_class_vars() and get_class_methods().
<?php
//function declaration
function trumpet() {
print 'OK';
}
// call to the function trumpet
trumpet();
?>
See Also
- Difference Between Declaration and Definition in Programming
- Difference Between Declaration and Definition