Syntax for default parameters in PHP functions

function can define C + +the default values for the style scalar parameters are as follows: Example#3 Using default parameters in functions<?PHPfunctionMakecoffee ($type= "Cappuccino"){    return"Making a cup of$type. \ n ";}EchoMakecoffee ();EchoMakecoffee (NULL);EchoMakecoffee ("Espresso");?>The above routines will output: Making a cup of cappuccino.Making a cup of.Making a cup of espresso.PHP also allows the use of arraysArrayand special typesNULLas the default parameter, for example: Example#4 Using non-scalar types as default parameters<?PHPfunctionMakecoffee ($types=Array("Cappuccino"),$coffeeMaker=NULL){    $device=Is_null($coffeeMaker) ? "Hands":$coffeeMaker; return"Making a cup of".Join(", ",$types). "With$device. \ n ";}EchoMakecoffee ();EchoMakecoffee (Array("Cappuccino", "Lavazza"), "teapot");?>The default value must be a constant expression, not such as a variable, a class member, or a function call. Note When you use the default parameters, any default arguments must be placed to the right of any non-default parameters, otherwise the function will not work as expected. Consider the following code snippet: Example#5 Incorrect usage of function default parameters<?PHPfunctionMakeyogurt ($type= "Acidophilus",$flavour){    return"Making a bowl of$type $flavour. \ n ";}EchoMakeyogurt ("Raspberry");//won ' t work as expected?>The above routines will output: Warning: Missing argument 2In the Makeyogurt () in/usr/local/etc/httpd/htdocs/phptest/functest.html on line 41Making a bowl of raspberry.now, compare the above example and this example: Example#6 Proper usage of function default parameters<?PHPfunctionMakeyogurt ($flavour,$type= "Acidophilus"){    return"Making a bowl of$type $flavour. \ n ";}EchoMakeyogurt ("Raspberry");//works as expected?>The above routines will output: Making a bowl of acidophilus raspberry.Note: The referenced parameters can also have default values since PHP 5.

Syntax for default parameters in PHP functions