{"id":4721,"date":"2024-03-14T01:52:29","date_gmt":"2024-03-14T01:52:29","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-to-implement-binary-file-output-in-the-c-language\/"},"modified":"2025-07-31T12:22:29","modified_gmt":"2025-07-31T12:22:29","slug":"how-to-implement-binary-file-output-in-the-c-language","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-to-implement-binary-file-output-in-the-c-language\/","title":{"rendered":"C Binary File Output: Using fwrite()"},"content":{"rendered":"<p>In C language, to output data in binary form to a file, you can use the fwrite() function. The prototype of the fwrite() function is as follows:<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-type\">size_t<\/span> <span class=\"hljs-title function_\">fwrite<\/span><span class=\"hljs-params\">(<span class=\"hljs-type\">const<\/span> <span class=\"hljs-type\">void<\/span> *ptr, <span class=\"hljs-type\">size_t<\/span> size, <span class=\"hljs-type\">size_t<\/span> nmemb, FILE *stream)<\/span>;\r\n<\/code><\/pre>\n<p>ptr is a pointer to the data to be written, size is the size of each data item in bytes, nmemb is the number of data items to be written, and stream is a pointer to the file to be written to.<\/p>\n<p>Here is a simple example demonstrating how to output data to a file in binary format.<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-meta\">#<span class=\"hljs-keyword\">include<\/span> <span class=\"hljs-string\">&lt;stdio.h&gt;<\/span><\/span>\r\n\r\n<span class=\"hljs-type\">int<\/span> <span class=\"hljs-title function_\">main<\/span><span class=\"hljs-params\">()<\/span> {\r\n    FILE *fp;\r\n    <span class=\"hljs-type\">int<\/span> data[] = {<span class=\"hljs-number\">1<\/span>, <span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">3<\/span>, <span class=\"hljs-number\">4<\/span>, <span class=\"hljs-number\">5<\/span>};\r\n\r\n    fp = fopen(<span class=\"hljs-string\">\"output.bin\"<\/span>, <span class=\"hljs-string\">\"wb\"<\/span>);\r\n    <span class=\"hljs-keyword\">if<\/span> (fp == <span class=\"hljs-literal\">NULL<\/span>) {\r\n        <span class=\"hljs-built_in\">printf<\/span>(<span class=\"hljs-string\">\"Error opening file\\n\"<\/span>);\r\n        <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-number\">1<\/span>;\r\n    }\r\n\r\n    fwrite(data, <span class=\"hljs-keyword\">sizeof<\/span>(<span class=\"hljs-type\">int<\/span>), <span class=\"hljs-number\">5<\/span>, fp);\r\n\r\n    fclose(fp);\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 this example, we define an integer array called data, and then open a file named &#8220;output.bin&#8221; in binary write mode (&#8220;wb&#8221;). Next, we use the fwrite() function to write the data from the integer array data into the file in binary format. Finally, we close the file.<\/p>\n<p>After running the program, the file &#8220;output.bin&#8221; will store the data from the integer array data in binary format.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In C language, to output data in binary form to a file, you can use the fwrite() function. The prototype of the fwrite() function is as follows: size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream); ptr is a pointer to the data to be written, size is the size of each data item [&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":[4499,331,381,380,855],"class_list":["post-4721","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-binary-files","tag-c-language","tag-c-programming","tag-file-i-o","tag-fwrite"],"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 Binary File Output: Using fwrite() - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Learn how to implement binary file output in C using fwrite(). 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