The components of a PHP function: a detailed explanation

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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