User-Defined Function with Default Parameter:
In PHP, a User-Defined Function with Default Parameters allows you to define default values for one or more parameters in the function declaration. If a value is not provided for a parameter during the function call, the default value is used. This feature enhances the flexibility of the function by providing reasonable default values while allowing customization when needed.
Example:
// User-Defined Function with Default Parameter
function greetUser($name = "Guest") {
echo "Hello, $name!";
}
// Calling the function without providing a name
greetUser();
// Output: Hello, Guest!
// Calling the function with a specific name
greetUser("John");
// Output: Hello, John!
In this example, the greetUser function has a parameter $name with a default value of "Guest". When the function is called without providing a value for $name, it uses the default value, resulting in a greeting for a guest. If a specific name is provided during the function call, that name is used instead.
Key Points:
Default Parameter Syntax:
function functionName($param1, $param2 = defaultValue, $param3, ...) {
// Function body
}
Default Parameters must be at the end:
If a function has parameters with default values, they must be placed at the end of the parameter list. Non-default parameters cannot follow default parameters.
Providing Values during Function Call:
When calling a function with default parameters, you can either provide values for all parameters or only for the ones you want to override. If a value is provided during the call, it takes precedence over the default value.