{"id":28075,"date":"2022-12-28T10:09:23","date_gmt":"2022-12-28T04:39:23","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-reading-files-in-bytes-closed\/"},"modified":"2022-12-28T10:09:23","modified_gmt":"2022-12-28T04:39:23","slug":"solved-reading-files-in-bytes-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-reading-files-in-bytes-closed\/","title":{"rendered":"[Solved] Reading files in bytes [closed]"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-64597882\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"64597882\" data-parentid=\"64597510\" data-score=\"-2\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>Thanks to the comments above, the problem is <code>if f, err := os.OpenFile( ...)<\/code> defines a new variable <code>f<\/code>, this new variable is not used. There are two potential solutions:<\/p>\n<pre class=\"lang-golang prettyprint-override\"><code>f, err := os.OpenFile(fn, os.O_RDWR, 0)\nif err != nil {\n    log.Fatal(\"error\", err)\n}\n<\/code><\/pre>\n<p>Or<\/p>\n<pre class=\"lang-golang prettyprint-override\"><code>var f *os.File\nvar err error\nif f, err = os.OpenFile(fn, os.O_RDWR, 0); err != nil {\n    log.Fatal(\"error\", err)\n}\n<\/code><\/pre>\n<p>So, my full working code now is:<\/p>\n<pre class=\"lang-golang prettyprint-override\"><code>package main\n\nimport (\n    \"fmt\"\n    \"io\/ioutil\"\n    \"log\"\n    \"os\"\n    \"strings\"\n    \"sync\"\n)\n\nfunc clean(files ...string) {\n    var wg sync.WaitGroup\n    for _, fn := range files {\n        wg.Add(1) \/\/ Launch several goroutines and increment the WaitGroup counter for each.\n        go worker(fn, &amp;wg)\n    }\n    wg.Wait()\n}\n\nfunc main() {\n    files := []string{\"currentInvenory.csv\", \"currentTransactions.csv\"}\n    clean(files...)\n\n}\n\nfunc worker(fn string, wg *sync.WaitGroup) {\n    defer wg.Done()\n\n    var f *os.File\n    var err error\n    if f, err = os.OpenFile(fn, os.O_RDWR, 0); err != nil {\n        log.Fatal(\"error\", err)\n    }\n\n    defer func() {\n        if err := f.Close(); err != nil {\n            log.Fatal(\"error\", err)\n        }\n    }()\n\n    if fileBytes, err := ioutil.ReadAll(f); err != nil {\n        log.Fatal(\"error\", err)\n    } else {\n        lines := strings.Split(string(fileBytes), \"\\n\")\n        if fn == \"currentInvenory.csv\" {\n            lines = lines[11 : len(lines)-6]\n        } else {\n            lines = lines[11 : len(lines)-7]\n        }\n        fmt.Println(fn, \"has a total of\", len(lines), \"lines\")\n        if len(lines) &gt; 0 {\n            var ctx = []byte{}\n            for _, s := range lines {\n                ctx = append(ctx, []byte(s)...)\n            }\n            ioutil.WriteFile(fn, ctx, 0644) \/\/ want (string, []byte, os.FileMode)\n        }\n    }\n\n}\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\"><\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Reading files in bytes [closed] <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] Thanks to the comments above, the problem is if f, err := os.OpenFile( &#8230;) defines a new variable f, this new variable is not used. There are two potential solutions: f, err := os.OpenFile(fn, os.O_RDWR, 0) if err != nil { log.Fatal(&#8220;error&#8221;, err) } Or var f *os.File var err error if f, err &#8230; <a title=\"[Solved] Reading files in bytes [closed]\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-reading-files-in-bytes-closed\/\" aria-label=\"More on [Solved] Reading files in bytes [closed]\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[596],"class_list":["post-28075","post","type-post","status-publish","format-standard","hentry","category-solved","tag-go"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Reading files in bytes [closed] - JassWeb<\/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:\/\/jassweb.com\/solved\/solved-reading-files-in-bytes-closed\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Reading files in bytes [closed] - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] Thanks to the comments above, the problem is if f, err := os.OpenFile( ...) defines a new variable f, this new variable is not used. There are two potential solutions: f, err := os.OpenFile(fn, os.O_RDWR, 0) if err != nil { log.Fatal(&quot;error&quot;, err) } Or var f *os.File var err error if f, err ... 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There are two potential solutions: f, err := os.OpenFile(fn, os.O_RDWR, 0) if err != nil { log.Fatal(\"error\", err) } Or var f *os.File var err error if f, err ... 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