The concept of php function

The concept of php function

PHP user-defined function

● In addition to the built-in PHP functions, we can create our own functions.

● Functions are blocks of statements that can be used repeatedly in a program.

● The function will not be executed immediately when the page is loaded.

● Functions will only be executed when called.

Recommended tutorial: PHP video tutorial

Creating user-defined functions in PHP

User-defined functions are declared with the word " function" starts with:

Syntax

function functionName() {
  被执行的代码;
}

Note: Function names can start with letters or underscores (not numbers).

Note: Function names are not case sensitive.

Tip: The function name should reflect the task performed by the function.

In the following example, we create a function named "writeMsg()". An opening brace ({) indicates the beginning of a function's code, while a closing brace (}) indicates the end of the function. This function outputs "Hello world!". To call this function, just use the function name:

Instance

<?php
function sayHi() {
  echo "Hello world!";
}
sayhi(); // 调用函数
?>

Output:

Hello world!

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