what is php function

A function refers to a program that is put together to do a certain thing. Also called subroutine, (in OOP) method.

The real power of PHP comes from its functions: it has over 1000 built-in functions.

PHP User-Defined Functions

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

A function is a block of statements that can be used repeatedly in a program.

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

Function will only be executed when called. (Recommended learning: PHP programming from entry to proficiency)

Creating user-defined functions in PHP

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

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:

Example

<?php
function sayHi() {
  echo "Hello world!";
}

sayhi(); // 调用函数?>

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