{"id":6075,"date":"2024-03-14T03:47:16","date_gmt":"2024-03-14T03:47:16","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-freopen-function-in-c-language\/"},"modified":"2025-08-01T23:08:08","modified_gmt":"2025-08-01T23:08:08","slug":"what-is-the-usage-of-the-freopen-function-in-c-language","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-freopen-function-in-c-language\/","title":{"rendered":"C Language freopen Function Explained"},"content":{"rendered":"<p>The freopen function is used to reopen a file and associate it with a specified stream. Reopening a file can be used to change the input or output file of a stream, or to reopen a file after it has been closed.<\/p>\n<p>The function prototype is:<\/p>\n<pre class=\"post-pre\"><code>FILE *<span class=\"hljs-title function_\">freopen<\/span><span class=\"hljs-params\">(<span class=\"hljs-type\">const<\/span> <span class=\"hljs-type\">char<\/span> *filename, <span class=\"hljs-type\">const<\/span> <span class=\"hljs-type\">char<\/span> *mode, FILE *stream)<\/span>;\r\n<\/code><\/pre>\n<p>The function returns a pointer to the new file stream, with the filename as the name of the file to be reopened, mode as the specified access mode when opening the file, and stream as the stream to be reassigned.<\/p>\n<p>For example, if you want to redirect the standard input stream stdin to the file input.txt, you can use the following code:<\/p>\n<pre class=\"post-pre\"><code>freopen(<span class=\"hljs-string\">\"input.txt\"<\/span>, <span class=\"hljs-string\">\"r\"<\/span>, <span class=\"hljs-built_in\">stdin<\/span>);\r\n<\/code><\/pre>\n<p>From now on, all standard input operations will read data from the input.txt file.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The freopen function is used to reopen a file and associate it with a specified stream. Reopening a file can be used to change the input or output file of a stream, or to reopen a file after it has been closed. The function prototype is: FILE *freopen(const char *filename, const char *mode, FILE *stream); [&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":[698,381,890,7105,7106],"class_list":["post-6075","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-c-functions","tag-c-programming","tag-file-handling","tag-freopen","tag-stdio-h"],"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 Language freopen Function Explained - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Learn how the freopen function in C reopens files and changes stream associations. Complete guide with syntax and usage examples.\" \/>\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-freopen-function-in-c-language\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"C Language freopen Function Explained\" \/>\n<meta property=\"og:description\" content=\"Learn how the freopen function in C reopens files and changes stream associations. Complete guide with syntax and usage examples.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-freopen-function-in-c-language\/\" \/>\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=\"2024-03-14T03:47:16+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-08-01T23:08:08+00:00\" \/>\n<meta name=\"author\" content=\"Liam\" \/>\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=\"Liam\" \/>\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-freopen-function-in-c-language\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-freopen-function-in-c-language\/\"},\"author\":{\"name\":\"Liam\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/23786905eb7b377f45ddb01c17da7671\"},\"headline\":\"C Language freopen Function Explained\",\"datePublished\":\"2024-03-14T03:47:16+00:00\",\"dateModified\":\"2025-08-01T23:08:08+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-freopen-function-in-c-language\/\"},\"wordCount\":129,\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"keywords\":[\"C++ functions\",\"C++ Programming\",\"file handling\",\"freopen\",\"stdio.h\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-freopen-function-in-c-language\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-the-freopen-function-in-c-language\/\",\"name\":\"C Language freopen Function Explained - Blog - Silicon Cloud\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#website\"},\"datePublished\":\"2024-03-14T03:47:16+00:00\",\"dateModified\":\"2025-08-01T23:08:08+00:00\",\"description\":\"Learn how the freopen function in C reopens files and changes stream associations. 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