What are the two types of php functions?
The real power of PHP comes from its functions. Functions are divided into built-in functions and custom functions.
Built-in functions
The so-called PHP built-in functions are functions that have been defined in the library of the PHP program, such as echo, mysql_connect, include_once etc., just like the system functions in VC, such as cout, etc.
In PHP, more than 1,000 built-in functions are provided.
Custom functions
In addition to the built-in PHP functions, we can create our own functions.
● Functions are reusable blocks of code used to complete a specific task in the program;
● Functions can make the program more modular and have a good structure;
● After the function is defined, it can be called repeatedly in the program;
● The function will not be executed immediately when the page is loaded.
● Function will only be executed when called.
Creating user-defined functions in PHP
User-defined function declarations begin with the words "function
":
Syntax
function functionName() { 被执行的代码; }
Note: Function names can start with letters or underscores (not numbers). Function names are not case sensitive.
Tip: The function name should reflect the task performed by the function.
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!". If you need to call this function, just use the function name:
<?php function sayhi() { echo "Hello world!"; } sayhi(); ?>
Output:
Hello world!
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