{"id":18451,"date":"2022-10-31T20:59:16","date_gmt":"2022-10-31T15:29:16","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\/"},"modified":"2022-10-31T20:59:16","modified_gmt":"2022-10-31T15:29:16","slug":"solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\/","title":{"rendered":"[Solved] Speed up reading a file to multiple bytes array and copy the offsets by if statement"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-23878912\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"23878912\" data-parentid=\"23878458\" data-score=\"0\" 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>You might have fallen in the &#8220;I use bytes and arrays so I&#8217;m low level so the code will be fast&#8221; trap. C# and .NET provide its users with efficient abstractions to avoid this, in this case probably a <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/msdn.microsoft.com\/en-us\/library\/System.IO.BinaryReader%28v=vs.110%29.aspx\">BinaryReader<\/a> and its <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/msdn.microsoft.com\/en-us\/library\/system.io.binaryreader.readstring%28v=vs.110%29.aspx\">ReadString<\/a> method.<\/p>\n<p>You code has problems:<\/p>\n<ul>\n<li>You don&#8217;t read the entire file (you stop at the last buffer of 1048576 bytes filled up, the next x bytes wont be read)<\/li>\n<li>You read a byte array then convert it to string ? you should use the .NET framework IO API (Streams) and allocate strings directly<\/li>\n<li>You should encapsulate IO operations on files in a &#8216;using&#8217; statement to avoid resources leaks (on file handles).<\/li>\n<\/ul>\n<p>Performance issues I see:<\/p>\n<ul>\n<li>Allocation of a big bytes array for nothing<\/li>\n<li>Convert calls that can be avoided<\/li>\n<\/ul>\n<p>Code sample (I did not compile it but it gives you the idea of a clean and efficient file reading, see my MSDN links for more examples)<\/p>\n<pre><code>string myText = string.Empty;\nusing(var reader = new BinaryReader(openFileDialog1.FileName))\n{\n  string line;\n  while((line = reader.ReadString()) != null)\n  {\n    myText += YouLogic(line); \/\/ use a StringBuilder if the number of string concatenations is high\n  }\n}\n<\/code><\/pre>\n<p>As a side note, for very big files, please consider using <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/msdn.microsoft.com\/en-us\/library\/dd997372%28v=vs.110%29.aspx\">C# Memory Mapped Files<\/a><\/p>\n<p>EDIT:<br \/>\nBinaryReader contains Read methods for all the needed data types, it should allow you to efficiently read any type of binary file.<\/p>\n<p>As for you additional question, look at <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/msdn.microsoft.com\/en-us\/library\/system.io.binaryreader.readbytes%28v=vs.110%29.aspx\">ReadBytes<\/a> from MSDN:<\/p>\n<pre><code>\/\/Offset 100 bytes:\nvar offsetRead = reader.ReadBytes(100);\n\/\/ read one byte\nbyte readByte = reader.ReadByte();\n\/\/ compare it to the expected value\nif(readByte == myByte)\n{\n   \/\/ copy the offset read\n   var myArray = new byte[100];\n   Array.Copy(offsetRead, myArray, offsetRead.Length);\n   DoSomething(myArray);\n}\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">3<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Speed up reading a file to multiple bytes array and copy the offsets by if statement <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] You might have fallen in the &#8220;I use bytes and arrays so I&#8217;m low level so the code will be fast&#8221; trap. C# and .NET provide its users with efficient abstractions to avoid this, in this case probably a BinaryReader and its ReadString method. You code has problems: You don&#8217;t read the entire file &#8230; <a title=\"[Solved] Speed up reading a file to multiple bytes array and copy the offsets by if statement\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\/\" aria-label=\"More on [Solved] Speed up reading a file to multiple bytes array and copy the offsets by if statement\">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":[4464,324],"class_list":["post-18451","post","type-post","status-publish","format-standard","hentry","category-solved","tag-bytearray","tag-c"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.4 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>[Solved] Speed up reading a file to multiple bytes array and copy the offsets by if statement - 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-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Speed up reading a file to multiple bytes array and copy the offsets by if statement - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] You might have fallen in the &#8220;I use bytes and arrays so I&#8217;m low level so the code will be fast&#8221; trap. C# and .NET provide its users with efficient abstractions to avoid this, in this case probably a BinaryReader and its ReadString method. You code has problems: You don&#8217;t read the entire file ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-10-31T15:29:16+00:00\" \/>\n<meta name=\"author\" content=\"Kirat\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Kirat\" \/>\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:\\\/\\\/jassweb.com\\\/solved\\\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\\\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/person\\\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] Speed up reading a file to multiple bytes array and copy the offsets by if statement\",\"datePublished\":\"2022-10-31T15:29:16+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\\\/\"},\"wordCount\":243,\"publisher\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#organization\"},\"keywords\":[\"bytearray\",\"c++\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\\\/\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-speed-up-reading-a-file-to-multiple-bytes-array-and-copy-the-offsets-by-if-statement\\\/\",\"name\":\"[Solved] Speed up reading a file to multiple bytes array and copy the offsets by if statement - 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