Syntax and structure of PHP functions

PHP function syntax includes function declaration (function_name and parameter list) and function body (containing the code to be executed). Functions can define a return value type, and if it is not defined, NULL is returned. Examples include calculating the sum of two numbers and checking whether a string contains another string.

The syntax and structure of PHP function

Grammar

The syntax of PHP function is as follows:

function [修饰符] function_name([参数列表]) {
  // 函数体
}

Where:

• [Modifier] is optional and can be public, private, protected or static.
• function_name is the name of the function.
• [Parameter List] is optional and contains the list of parameters accepted by the function.
• The function body is the block of code that contains the code to be executed by the function.

Structure

PHP function consists of the following parts:

• Function declaration: Contains function header (function, [modifier] and function_name) and parameter list.
• Function body: Contains the code to be executed by the function.
• Function return value: If the function defines a return value type, the function will return a value of that type. If the return type is not defined, the function returns NULL.

Practical case

Example 1:Calculate the sum of two numbers

function add($num1, $num2) {
  return $num1 + $num2;
}

$result = add(10, 15);
echo $result; // 输出：25

Example 2:Judge one Whether a string contains another string

function contains($str, $subStr) {
  return strpos($str, $subStr) !== false;
}

$contains_result = contains("Hello world", "world");
echo $contains_result ? '包含' : '不包含'; // 输出：包含

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