{"id":83,"date":"2020-12-12T09:16:01","date_gmt":"2020-12-12T09:16:01","guid":{"rendered":"https:\/\/www.kindsonthegenius.com\/php\/?p=83"},"modified":"2026-10-29T01:28:57","modified_gmt":"2026-10-29T01:28:57","slug":"php-functions","status":"publish","type":"post","link":"https:\/\/kindsonthegenius.com\/php\/php-functions\/","title":{"rendered":"PHP – Functions"},"content":{"rendered":"

In this tutorial, we would talk about the important concept of functions in PHP. Function in PHP work similar to other languages like Python and Perl. A function is a block of code that performs some actions and returns a result.<\/p>\n

Previously, we discussed two inbuilt functions: fopen() an fread()<\/a>.\u00a0 Now we would see how to create our own functions. You will learn the following:<\/p>\n

    \n
  1. Creating a Function<\/li>\n
  2. Function Parameters<\/a><\/li>\n
  3. Arguments by Reference<\/a><\/li>\n
  4. PHP Function Return Values<\/a><\/li>\n
  5. Default Function Parameters<\/a><\/li>\n
  6. Calling Functions Dynamically<\/a><\/li>\n<\/ol>\n

     <\/p>\n

    1. Creating a Function<\/strong><\/h4>\n

    To create a function in PHP, you use the function<\/strong> keyword. Then inside curly braces, you write the code to be executed by the function. After creating a function, you can use it by calling it.<\/p>\n

    Let’s take a simple example. We write a function that displays a simple message out to the browser.<\/p>\n

    <?php<\/span>\r\n    \/* Defining a Function *\/<\/span>\r\n    function<\/span> showMessage<\/span>() {\r\n    echo<\/span> \"You are learning about PHP Functions!\"<\/span>;\r\n    }\r\n    \r\n    \/* Calling the Function *\/<\/span>\r\n    showMessage();\r\n?><\/span>\r\n<\/pre>\n
    This function will execute and display the output on the browser<\/p>\n
    You are learning about PHP Functions!\r\n<\/pre>\n
     <\/p>\n
    2. Function Parameters<\/strong><\/h4>\n
    Parameter allow you to provides some data for the function to work with. They are like inputs to a function. You specify the function parameters in brackets before the body of the functions.<\/p>\n
    <?php<\/span>\r\n    \/* Function to multiply two numbers *\/<\/span>\r\n    function<\/span> multiply<\/span>($number1<\/span>, $number2<\/span>) {\r\n        $product<\/span> =<\/span> $number1<\/span> *<\/span> $number2<\/span>;\r\n        echo<\/span> \"Product of <\/span>$number1<\/span> and <\/span>$number2<\/span> is <\/span>$product<\/span>\"<\/span>;\r\n    }\r\n    \r\n    \/* Calling the Function *\/<\/span>\r\n    multiply(5<\/span>, 10<\/span>);\r\n?><\/span>\r\n<\/pre>\n
    As an exercise, execute the code and tell me what output you have!<\/p>\n
     <\/p>\n
    3. Arguments by Reference<\/strong><\/h4>\n
    In PHP, you can pass parameters to functions by reference. This means that the argument given to the function is a reference to the variable. Therefore the function manipulates this reference rather than the actual value.<\/p>\n
    If the function makes any changes to the arguments, the change would reflect on the original value of the variable. To pass an argument by reference, you simply add an ampersand(&) to the variable name.<\/p>\n
    <?php<\/span>\r\n    \/* Function to multiply two numbers *\/<\/span>\r\n    function<\/span> addTen<\/span>(&<\/span>$number<\/span>) {\r\n        $number<\/span> +=<\/span> 10<\/span>;\r\n    }\r\n\r\n    function<\/span> addTwenty<\/span>(&<\/span>$number<\/span>) {\r\n        $number<\/span> +=<\/span> 20<\/span>;\r\n    }\r\n    \r\n    \/* Calling the Function *\/<\/span>\r\n    $originalValue<\/span> =<\/span> 10<\/span>;\r\n    addTen($originalValue<\/span>);\r\n    \r\n    echo<\/span> \"Original Value: <\/span>$originalValue<\/span><br \/>\"<\/span>;\r\n    \r\n    addTwenty( $originalValue<\/span> );\r\n    echo<\/span> \"Original Value: <\/span>$originalValue<\/span><br \/>\"<\/span>;\r\n?><\/span>\r\n<\/pre>\n
    The output of the program is:<\/p>\n
    Original Value: 20\r\nOriginal Value: 40\r\n<\/pre>\n
    What happens here is that the original value is changed by each of the functions. By the first function call, the values changes from 10 to 20 by the addTen()<\/strong> <\/em>function. The second function addTwenty()<\/strong><\/em> changes the value again from 20 to 40. So you see that the calls are made using reference to the original value.<\/p>\n
     <\/p>\n
    4. PHP Function Return Values<\/strong><\/h4>\n
    A function could also return some value as result of its operation. This is specified using the return<\/strong> statement. When the function encounters a return statement, it stops execution and sends the value back to the calling code.\u00a0Also, more than one value can be returned using a return array().<\/p>\n
    The code below, takes two numbers, multiplies them and returns the result back to the calling program.<\/p>\n
    <?php<\/span>\r\n    \/\/Returning value<\/span>\r\n    function<\/span> multiply<\/span>($val1<\/span>, $val2<\/span>) {\r\n        $product<\/span> =<\/span> $val1<\/span> *<\/span> $val2<\/span>;\r\n        return<\/span> $product<\/span>;\r\n    }\r\n\r\n    $result<\/span> =<\/span> multiply(15<\/span>, 3<\/span>);\r\n    echo<\/span> \"The return value is: <\/span>$result<\/span>\"<\/span>;\r\n?><\/span>\r\n<\/pre>\n
     <\/p>\n
    5. Default Function Parameters<\/strong><\/h4>\n
    Sometimes you may need to specify a default value for a function parameter. So in case the calling function does not pass any parameter but the function needs a parameter, then the default values are used.<\/p>\n
    The function below outputs 0 case a parameter was not passed.<\/p>\n
    <?php<\/span>\r\n    \/\/Funtion's default value<\/span>\r\n    function<\/span> showNum<\/span>($default<\/span> =<\/span> 0<\/span>) {\r\n        echo<\/span> \"Total input is <\/span>$default<\/span> <br>\"<\/span>;\r\n    }\r\n\r\n    showNum(10<\/span>);\r\n    showNum();\r\n?><\/span>\r\n<\/pre>\n
    The output is:
    \n<\/p>\n
    Total input is 10\r\nTotal input is 0\r\n<\/pre>\n
    In the first line the function uses the passed in parameter of 10 while in the second line, it uses the default parameter of 0.<\/p>\n
     <\/p>\n
    6. Calling Functions Dynamically<\/strong><\/h4>\n
    You can call a function dynamically. This means that you can assign a function name as string to variables. Then that variable can then be used in place of the function name. An example is given below:<\/p>\n
    <?php<\/span>\r\n    \/\/Assigning functions to variables<\/span>\r\n    function<\/span> welcome<\/span>($name<\/span>) {\r\n        echo<\/span> \"Hey <\/span>$name<\/span>, you are welcome\"<\/span>;\r\n    }\r\n\r\n    $functionVar<\/span> =<\/span> \"welcome\"<\/span>;\r\n    $functionVar<\/span>(\"Kindson\"<\/span>);\r\n?><\/span>\r\n<\/pre>\n
    This also works fine. Try it and see the output<\/p>\n","protected":false},"excerpt":{"rendered":"
    In this tutorial, we would talk about the important concept of functions in PHP. Function in PHP work similar to other languages like Python and … <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[1],"tags":[13],"class_list":["post-83","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-functions-in-php"],"yoast_head":"\nPHP - Functions | Kindson The Genius<\/title>\n<meta name=\"description\" content=\"PHP - Functions \u2014 free PHP tutorial by Kindson Munonye with clear examples. Step-by-step for beginners. Part of Kindson The Genius. Free online.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/kindsonthegenius.com\/php\/php-functions\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"PHP - Functions | Kindson The Genius\" \/>\n<meta property=\"og:description\" content=\"PHP - Functions \u2014 free PHP tutorial by Kindson Munonye with clear examples. Step-by-step for beginners. Part of Kindson The Genius. Free online.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/kindsonthegenius.com\/php\/php-functions\/\" \/>\n<meta property=\"og:site_name\" content=\"PHP Tutorial\" \/>\n<meta property=\"article:published_time\" content=\"2020-12-12T09:16:01+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-10-29T01:28:57+00:00\" \/>\n<meta name=\"author\" content=\"kindsonthegenius\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"kindsonthegenius\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/\"},\"author\":{\"name\":\"kindsonthegenius\",\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/#\\\/schema\\\/person\\\/a2dcea4c76668e90e5842583fd5a5f60\"},\"headline\":\"PHP – Functions\",\"datePublished\":\"2020-12-12T09:16:01+00:00\",\"dateModified\":\"2026-10-29T01:28:57+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/\"},\"wordCount\":539,\"keywords\":[\"Functions in PHP\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/\",\"url\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/\",\"name\":\"PHP - Functions | Kindson The Genius\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/#website\"},\"datePublished\":\"2020-12-12T09:16:01+00:00\",\"dateModified\":\"2026-10-29T01:28:57+00:00\",\"author\":{\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/#\\\/schema\\\/person\\\/a2dcea4c76668e90e5842583fd5a5f60\"},\"description\":\"PHP - Functions \u2014 free PHP tutorial by Kindson Munonye with clear examples. Step-by-step for beginners. Part of Kindson The Genius. Free online.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/php-functions\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"PHP – Functions\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/#website\",\"url\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/\",\"name\":\"PHP Tutorial\",\"description\":\"Beginner to Expert With Practicals\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/#\\\/schema\\\/person\\\/a2dcea4c76668e90e5842583fd5a5f60\",\"name\":\"kindsonthegenius\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/b9d710de456c3d85e5614c3a6992fa3d527425e2ab32b8bd5d85bfbaa235004b?s=96&d=mm&r=g\",\"url\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/b9d710de456c3d85e5614c3a6992fa3d527425e2ab32b8bd5d85bfbaa235004b?s=96&d=mm&r=g\",\"contentUrl\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/b9d710de456c3d85e5614c3a6992fa3d527425e2ab32b8bd5d85bfbaa235004b?s=96&d=mm&r=g\",\"caption\":\"kindsonthegenius\"},\"url\":\"https:\\\/\\\/kindsonthegenius.com\\\/php\\\/author\\\/kindsonthegenius-3\\\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"PHP - Functions | Kindson The Genius","description":"PHP - Functions \u2014 free PHP tutorial by Kindson Munonye with clear examples. Step-by-step for beginners. Part of Kindson The Genius. Free online.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/kindsonthegenius.com\/php\/php-functions\/","og_locale":"en_US","og_type":"article","og_title":"PHP - Functions | Kindson The Genius","og_description":"PHP - Functions \u2014 free PHP tutorial by Kindson Munonye with clear examples. Step-by-step for beginners. Part of Kindson The Genius. Free online.","og_url":"https:\/\/kindsonthegenius.com\/php\/php-functions\/","og_site_name":"PHP Tutorial","article_published_time":"2020-12-12T09:16:01+00:00","article_modified_time":"2026-10-29T01:28:57+00:00","author":"kindsonthegenius","twitter_card":"summary_large_image","twitter_misc":{"Written by":"kindsonthegenius","Est. reading time":"3 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/kindsonthegenius.com\/php\/php-functions\/#article","isPartOf":{"@id":"https:\/\/kindsonthegenius.com\/php\/php-functions\/"},"author":{"name":"kindsonthegenius","@id":"https:\/\/kindsonthegenius.com\/php\/#\/schema\/person\/a2dcea4c76668e90e5842583fd5a5f60"},"headline":"PHP – Functions","datePublished":"2020-12-12T09:16:01+00:00","dateModified":"2026-10-29T01:28:57+00:00","mainEntityOfPage":{"@id":"https:\/\/kindsonthegenius.com\/php\/php-functions\/"},"wordCount":539,"keywords":["Functions in PHP"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/kindsonthegenius.com\/php\/php-functions\/","url":"https:\/\/kindsonthegenius.com\/php\/php-functions\/","name":"PHP - Functions | Kindson The Genius","isPartOf":{"@id":"https:\/\/kindsonthegenius.com\/php\/#website"},"datePublished":"2020-12-12T09:16:01+00:00","dateModified":"2026-10-29T01:28:57+00:00","author":{"@id":"https:\/\/kindsonthegenius.com\/php\/#\/schema\/person\/a2dcea4c76668e90e5842583fd5a5f60"},"description":"PHP - Functions \u2014 free PHP tutorial by Kindson Munonye with clear examples. Step-by-step for beginners. Part of Kindson The Genius. Free online.","breadcrumb":{"@id":"https:\/\/kindsonthegenius.com\/php\/php-functions\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/kindsonthegenius.com\/php\/php-functions\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/kindsonthegenius.com\/php\/php-functions\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/kindsonthegenius.com\/php\/"},{"@type":"ListItem","position":2,"name":"PHP – Functions"}]},{"@type":"WebSite","@id":"https:\/\/kindsonthegenius.com\/php\/#website","url":"https:\/\/kindsonthegenius.com\/php\/","name":"PHP Tutorial","description":"Beginner to Expert With Practicals","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/kindsonthegenius.com\/php\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/kindsonthegenius.com\/php\/#\/schema\/person\/a2dcea4c76668e90e5842583fd5a5f60","name":"kindsonthegenius","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/secure.gravatar.com\/avatar\/b9d710de456c3d85e5614c3a6992fa3d527425e2ab32b8bd5d85bfbaa235004b?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/b9d710de456c3d85e5614c3a6992fa3d527425e2ab32b8bd5d85bfbaa235004b?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/b9d710de456c3d85e5614c3a6992fa3d527425e2ab32b8bd5d85bfbaa235004b?s=96&d=mm&r=g","caption":"kindsonthegenius"},"url":"https:\/\/kindsonthegenius.com\/php\/author\/kindsonthegenius-3\/"}]}},"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/posts\/83","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/comments?post=83"}],"version-history":[{"count":1,"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/posts\/83\/revisions"}],"predecessor-version":[{"id":84,"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/posts\/83\/revisions\/84"}],"wp:attachment":[{"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/media?parent=83"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/categories?post=83"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/php\/wp-json\/wp\/v2\/tags?post=83"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}