{"id":10041,"date":"2024-03-14T10:29:18","date_gmt":"2024-03-14T10:29:18","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/"},"modified":"2025-08-03T18:26:56","modified_gmt":"2025-08-03T18:26:56","slug":"what-is-the-usage-of-the-define-function-in-php","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/","title":{"rendered":"PHP Define Function Guide"},"content":{"rendered":"<p>The define function in PHP is used to define a constant. Constants remain unchanged throughout the script execution and cannot be reassign. The syntax of the define function is as follows:<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-title function_ invoke__\">define<\/span>(name, value, case_insensitive);\r\n<\/code><\/pre>\n<p>Among them:<\/p>\n<ol>\n<li>name: the name of the constant<\/li>\n<li>value: the constant&#8217;s value<\/li>\n<li>Case_insensitive is an optional parameter that, if set to true, means that constant names are not case-sensitive. By default, it is set to false.<\/li>\n<\/ol>\n<p>Original: \u6211\u9700\u8981\u4e00\u53f0\u65b0\u7684\u7535\u8111\u3002<br \/>\nParaphrased: I need a new computer.<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-title function_ invoke__\">define<\/span>(<span class=\"hljs-string\">\"PI\"<\/span>, <span class=\"hljs-number\">3.14<\/span>);\r\n<span class=\"hljs-keyword\">echo<\/span> PI; <span class=\"hljs-comment\">\/\/ \u8f93\u51fa 3.14<\/span>\r\n<\/code><\/pre>\n<p>Constant names are usually written in uppercase letters and do not require the use of the dollar sign.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The define function in PHP is used to define a constant. Constants remain unchanged throughout the script execution and cannot be reassign. The syntax of the define function is as follows: define(name, value, case_insensitive); Among them: name: the name of the constant value: the constant&#8217;s value Case_insensitive is an optional parameter that, if set to [&hellip;]<\/p>\n","protected":false},"author":10,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[10695,2908,12268,690,7762],"class_list":["post-10041","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-define-function","tag-php-constants","tag-php-define","tag-php-programming","tag-php-syntax"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>PHP Define Function Guide - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Learn to use PHP&#039;s define function to create constants. Understand syntax, parameters, and best practices.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"PHP Define Function Guide\" \/>\n<meta property=\"og:description\" content=\"Learn to use PHP&#039;s define function to create constants. Understand syntax, parameters, and best practices.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - Silicon Cloud\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/SiliCloudGlobal\/\" \/>\n<meta property=\"article:published_time\" content=\"2024-03-14T10:29:18+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-08-03T18:26:56+00:00\" \/>\n<meta name=\"author\" content=\"Jackson Davis\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:site\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Jackson Davis\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/\"},\"author\":{\"name\":\"Jackson Davis\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/55a10b8b0457c35884c25677889ad350\"},\"headline\":\"PHP Define Function Guide\",\"datePublished\":\"2024-03-14T10:29:18+00:00\",\"dateModified\":\"2025-08-03T18:26:56+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/\"},\"wordCount\":98,\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"keywords\":[\"define function\",\"PHP constants\",\"PHP define\",\"PHP programming\",\"PHP syntax\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-define-function-in-php\/\",\"name\":\"PHP Define Function Guide - Blog - Silicon Cloud\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#website\"},\"datePublished\":\"2024-03-14T10:29:18+00:00\",\"dateModified\":\"2025-08-03T18:26:56+00:00\",\"description\":\"Learn to use PHP's define function to create constants. 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