The real power of PHP comes from its functions. Show
PHP has more than 1000 built-in functions, and in addition you can create your own custom functions. PHP Built-in FunctionsPHP has over 1000 built-in functions that can be called directly, from within a script, to perform a specific task. Please check out our PHP reference for a complete overview of the PHP built-in functions. PHP User Defined FunctionsBesides the built-in PHP functions, it is possible to create your own functions.
Create a User Defined Function in PHPA user-defined function declaration starts with the word Syntax function functionName() { Note: A function name must start with a letter or an underscore. Function names are NOT case-sensitive. Tip: Give the function a name that reflects what the function does! In the example below, we create a function named "writeMsg()". The opening curly brace ( { ) indicates the beginning of the function code, and the closing curly brace ( } ) indicates the end of the function. The function outputs "Hello world!". To call the function, just write its name followed by brackets (): Example<?php writeMsg(); // call the function Try it Yourself » PHP Function ArgumentsInformation can be passed to functions through arguments. An argument is just like a variable. Arguments are specified after the function name, inside the parentheses. You can add as many arguments as you want, just separate them with a comma. The following example has a function with one argument ($fname). When the familyName() function is called, we also pass along a name (e.g. Jani), and the name is used inside the function, which outputs several different first names, but an equal last name: Example<?php familyName("Jani"); Try it Yourself » The following example has a function with two arguments ($fname and $year): Example<?php familyName("Hege", "1975"); Try it Yourself » PHP is a Loosely Typed LanguageIn the example above, notice that we did not have to tell PHP which data type the variable is. PHP automatically associates a data type to the variable, depending on its value. Since the data types are not set in a strict sense, you can do things like adding a string to an integer without causing an error. In PHP 7, type declarations were added. This gives us an option to specify the expected data type when declaring a function, and by adding the In the following example we try to send both a number
and a string to the function without using Example<?php Try it Yourself » To specify In the following example we try to send both a number and a string to the function, but here we have added the Example<?php declare(strict_types=1); // strict requirement function addNumbers(int $a, int $b) { Try it Yourself » The PHP Default Argument ValueThe following example shows how to use a default parameter. If we call the function setHeight() without arguments it takes the default value as argument: Example<?php declare(strict_types=1); // strict requirement setHeight(350); Try it Yourself » PHP Functions - Returning valuesTo let a function return a value, use the Example<?php
declare(strict_types=1); // strict requirement echo "5 + 10 = " . sum(5, 10) . "<br>"; Try it Yourself » PHP Return Type DeclarationsPHP 7 also supports Type Declarations
for the To declare a type for the function return, add a colon ( In the following example we specify the return type for the function: Example<?php declare(strict_types=1); // strict
requirement Try it Yourself » You can specify a different return type, than the argument types, but make sure the return is the correct type: Example<?php declare(strict_types=1); // strict requirement Try it Yourself » Passing Arguments by ReferenceIn PHP, arguments are usually passed by value, which means that a copy of the value is used in the function and the variable that was passed into the function cannot be changed. When a
function argument is passed by reference, changes to the argument also change the variable that was passed in. To turn a function argument into a reference, the ExampleUse a pass-by-reference argument to update a variable: <?php $num = 2; Try it Yourself » PHP ExercisesHow do you create a function using PHP?Create a User Defined Function in PHP
Note: A function name must start with a letter or an underscore. Function names are NOT case-sensitive. Tip: Give the function a name that reflects what the function does!
What is function in PHP with example?PHP function is a piece of code that can be reused many times. It can take input as argument list and return value. There are thousands of built-in functions in PHP. In PHP, we can define Conditional function, Function within Function and Recursive function also.
How do you create a function?To create a function, we must first declare it and give it a name, the same way we'd create any variable, and then we follow it by a function definition: var sayHello = function() { }; We could put any code inside that function - one statement, multiple statements - depends on what we want to do.
How do we call a function in PHP?In PHP, a function is declared with the function keyword prefixed with the function name and the calling of a function in a program is done by just calling the name of the function wherever required.
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