PHP functions can perform specific tasks, and their components include: access modifiers (public, private, protected) return type function name formal parameter list function body
Components of a PHP function: A detailed explanation
Introduction
A PHP function is a set of predefined blocks of code that perform a specific task. To create a custom function, you must specify the function name and its components.
Components of a function
A PHP function consists of the following parts:
1. Access modifier (optional)
-
#public
: Functions can be accessed from anywhere. -
private
: The function can only be accessed within the class in which it is defined. -
protected
: The function can only be accessed in the class in which it is defined and its derived classes.
2. Return type (optional)
- Specifies the type of value returned by the function. If the function returns no value,
void
is used.
3. Function name
- Give the function a unique and meaningful name.
4. Formal parameter list
- The parameter list received by the function, specify the data type and name of each parameter.
5. Function body
- The code body of the function, which contains the tasks to be performed.
Practical case
Create a function to calculate the sum of two numbers:
function sum($num1, $num2) { return $num1 + $num2; }
Call this function in a script:
$result = sum(5, 10); echo $result; // 输出:15
Other notes
- By default, functions are
public
accessible. - If the return type is not specified, the function will return
NULL
. - Formal parameter names are used as variables in the function body.
- Functions can be nested within other functions.
- Function declarations can be imported into other namespaces through the
use
declaration.
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