{"id":288,"date":"2019-10-19T03:56:42","date_gmt":"2019-10-19T03:56:42","guid":{"rendered":"https:\/\/golangbyexamples.com\/?p=288"},"modified":"2019-11-12T19:38:17","modified_gmt":"2019-11-12T19:38:17","slug":"read-large-file-line-by-line-go","status":"publish","type":"post","link":"https:\/\/golangbyexamples.com\/read-large-file-line-by-line-go\/","title":{"rendered":"Read a large file Line by Line in Go (Golang)"},"content":{"rendered":"\n<p class=\"has-medium-font-size\">When it comes to reading large files, obviously we don&#8217;t want to load the entire file in memory. bufio package in golang comes to the rescue when reading large files. Let&#8217;s say we have a sample.txt file with below contents<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">This is an example\nto show how\nto read file \nline by line.<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Here is the program:<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\nimport (\n    \"bufio\"\n    \"fmt\"\n    \"log\"\n    \"os\"\n)\nfunc main(){\n    LinebyLineScan()\n}\nfunc LinebyLineScan() {\n    file, err := os.Open(\".\/sample.txt\")\n    if err != nil {\n        log.Fatal(err)\n    }\n    defer file.Close()\n    scanner := bufio.NewScanner(file)\n    for scanner.Scan() {\n        fmt.Println(scanner.Text())\n    }\n    if err := scanner.Err(); err != nil {\n        log.Fatal(err)\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output:<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">This is an example\nto show how \nto read file \nline by line.<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Note however bufio.Scanner has max buffer size 64*1024 bytes which means in case you file has any line greater than the size of 64*1024, then it will give the error <\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">bufio.Scanner: token too long<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>When it comes to reading large files, obviously we don&#8217;t want to load the entire file in memory. bufio package in golang comes to the rescue when reading large files. Let&#8217;s say&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","footnotes":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false},"categories":[1],"tags":[38,3,39,41,40],"class_list":["post-288","post","type-post","status-publish","format-standard","hentry","category-tech","tag-file","tag-go","tag-largefile","tag-line-by-line","tag-linebyline"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.7 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Read a large file Line by Line in Go (Golang) - Welcome To Golang By Example<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/golangbyexamples.com\/read-large-file-line-by-line-go\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Read a large file Line by Line in Go (Golang) - Welcome To Golang By Example\" \/>\n<meta property=\"og:description\" content=\"When it comes to reading large files, obviously we don&#8217;t want to load the entire file in memory. bufio package in golang comes to the rescue when reading large files. 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