{"id":7441,"date":"2024-03-14T05:32:17","date_gmt":"2024-03-14T05:32:17","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-volatile-in-the-c-language\/"},"modified":"2025-08-02T16:17:21","modified_gmt":"2025-08-02T16:17:21","slug":"what-is-the-usage-of-volatile-in-the-c-language","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-volatile-in-the-c-language\/","title":{"rendered":"C volatile Keyword: Usage Explained"},"content":{"rendered":"<p>In the C language, the volatile keyword is used to inform the compiler that a variable may be unexpectedly modified during program execution, so the compiler should not optimize this variable and instead should always retrieve its value from memory. This prevents the compiler from storing the variable&#8217;s value in a register, ensuring that the program can correctly access the variable.<\/p>\n<p>The volatile keyword is commonly used in multi-threaded programming or hardware-related programming, such as in interrupt service routines where variables are often marked as volatile to ensure that the latest value of the variable can be correctly read when an interrupt occurs.<\/p>\n<p>\u793a\u4f8b\uff1aHere is an example. <\/p>\n<p>Word: \u6211\u7231\u4f60<br \/>\nOption: I love you<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">volatile<\/span> <span class=\"hljs-type\">int<\/span> flag = <span class=\"hljs-number\">0<\/span>;\r\n\r\n<span class=\"hljs-type\">void<\/span> <span class=\"hljs-title function_\">interrupt_handler<\/span><span class=\"hljs-params\">()<\/span>\r\n{\r\n    flag = <span class=\"hljs-number\">1<\/span>;\r\n}\r\n\r\n<span class=\"hljs-type\">int<\/span> <span class=\"hljs-title function_\">main<\/span><span class=\"hljs-params\">()<\/span>\r\n{\r\n    <span class=\"hljs-keyword\">while<\/span>(!flag)\r\n    {\r\n        <span class=\"hljs-comment\">\/\/ do something<\/span>\r\n    }\r\n    \r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-number\">0<\/span>;\r\n}\r\n<\/code><\/pre>\n<p>In the example above, the variable flag is declared volatile to ensure that the latest value of flag can be correctly read when an interrupt occurs.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the C language, the volatile keyword is used to inform the compiler that a variable may be unexpectedly modified during program execution, so the compiler should not optimize this variable and instead should always retrieve its value from memory. This prevents the compiler from storing the variable&#8217;s value in a register, ensuring that the [&hellip;]<\/p>\n","protected":false},"author":12,"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":[381,6985,9525,9197,9196],"class_list":["post-7441","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-c-programming","tag-compiler-optimization","tag-hardware-programming","tag-memory-access","tag-volatile"],"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>C volatile Keyword: Usage Explained - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Learn how volatile in C prevents compiler optimization for hardware\/multi-threaded programming. 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