{"id":8294,"date":"2024-03-14T07:52:56","date_gmt":"2024-03-14T07:52:56","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-to-find-the-position-of-a-substring-in-a-string-using-c-language\/"},"modified":"2025-08-03T02:58:00","modified_gmt":"2025-08-03T02:58:00","slug":"how-to-find-the-position-of-a-substring-in-a-string-using-c-language","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-to-find-the-position-of-a-substring-in-a-string-using-c-language\/","title":{"rendered":"C strstr(): Find Substring in String"},"content":{"rendered":"<p>In the C language, you can use the function strstr to locate the position of a substring within a string. The prototype of this function is as follows:<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-type\">char<\/span> *<span class=\"hljs-title function_\">strstr<\/span><span class=\"hljs-params\">(<span class=\"hljs-type\">const<\/span> <span class=\"hljs-type\">char<\/span> *haystack, <span class=\"hljs-type\">const<\/span> <span class=\"hljs-type\">char<\/span> *needle)<\/span>;\r\n<\/code><\/pre>\n<p>In this case, haystack is the string to be searched and needle is the substring to search for. The function returns the position of the first occurrence of the substring in the string, or NULL if the substring is not found.<\/p>\n<p>Here is an example code:<\/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<span class=\"hljs-meta\">#<span class=\"hljs-keyword\">include<\/span> <span class=\"hljs-string\">&lt;string.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    <span class=\"hljs-type\">const<\/span> <span class=\"hljs-type\">char<\/span> *haystack = <span class=\"hljs-string\">\"Hello, World!\"<\/span>;\r\n    <span class=\"hljs-type\">const<\/span> <span class=\"hljs-type\">char<\/span> *needle = <span class=\"hljs-string\">\"World\"<\/span>;\r\n    \r\n    <span class=\"hljs-type\">char<\/span> *result = <span class=\"hljs-built_in\">strstr<\/span>(haystack, needle);\r\n    \r\n    <span class=\"hljs-keyword\">if<\/span> (result) {\r\n        <span class=\"hljs-built_in\">printf<\/span>(<span class=\"hljs-string\">\"\u5b50\u4e32\u51fa\u73b0\u5728\u5b57\u7b26\u4e32\u7684\u4f4d\u7f6e\uff1a%ld\\n\"<\/span>, result - haystack);\r\n    } <span class=\"hljs-keyword\">else<\/span> {\r\n        <span class=\"hljs-built_in\">printf<\/span>(<span class=\"hljs-string\">\"\u672a\u627e\u5230\u5b50\u4e32\\n\"<\/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 code above, we are searching for the substring &#8220;World&#8221; in the string &#8220;Hello, World!&#8221;. If the substring is found, we will print its position in the string. If not found, we will print &#8220;Substring not found&#8221;.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the C language, you can use the function strstr to locate the position of a substring within a string. The prototype of this function is as follows: char *strstr(const char *haystack, const char *needle); In this case, haystack is the string to be searched and needle is the substring to search for. The function [&hellip;]<\/p>\n","protected":false},"author":7,"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":[10768,381,276,11091,3448],"class_list":["post-8294","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-c-string-functions","tag-c-programming","tag-string-manipulation","tag-strstr-c","tag-substring-search"],"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 strstr(): Find Substring in String - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Learn to use strstr() in C to locate substring positions. 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