{"id":1947,"date":"2020-04-08T11:25:23","date_gmt":"2020-04-08T11:25:23","guid":{"rendered":"https:\/\/golangbyexamples.com\/?p=1947"},"modified":"2020-04-08T11:25:55","modified_gmt":"2020-04-08T11:25:55","slug":"generate-random-string-golang","status":"publish","type":"post","link":"https:\/\/golangbyexamples.com\/generate-random-string-golang\/","title":{"rendered":"Generate a random string in Go (Golang)"},"content":{"rendered":"\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_17 counter-hierarchy counter-decimal ez-toc-light-blue\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" style=\"display: none;\"><i class=\"ez-toc-glyphicon ez-toc-icon-toggle\"><\/i><\/a><\/span><\/div>\n<nav><ul class=\"ez-toc-list ez-toc-list-level-1\"><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/golangbyexamples.com\/generate-random-string-golang\/#Overview\" title=\"Overview\">Overview<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/golangbyexamples.com\/generate-random-string-golang\/#Code\" title=\"Code\">Code<\/a><\/li><\/ul><\/nav><\/div>\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Overview\"><\/span><strong>Overview<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\"><strong>&#8216;mat\/rand&#8217; <\/strong>package of golang contains a <strong>Intn<\/strong> function that can be used to generate a pseudo-random number between [0,n). Bracket at the end means that n is exclusive. This function can be utilized to generate a random string from a character set.<\/p>\n\n\n\n<p class=\"has-medium-font-size\"><br>To know more about what pseudo-random number means, checkout this post &#8211; <a href=\"https:\/\/golangbyexamples.com\/generate-random-number-golang\">https:\/\/golangbyexamples.com\/generate-random-number-golang<\/a><\/p>\n\n\n\n<p class=\"has-medium-font-size\">Below is the signature of this method. It takes input a number n and will return a number x in range 0&lt;=x&lt;n.<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">func Intn(n int) int<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Above function can be used to generate a random string. Basically we first select a charSet. Then we use the above function to generate a random number and then use that random number to get a random character from the charSet. This random character is added to a string until we have a random string of desired length.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Code\"><\/span><strong>Code<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n    \"math\/rand\"\n    \"strings\"\n    \"time\"\n)\n\nfunc main() {\n    rand.Seed(time.Now().Unix())\n\n    \/\/Only lowercase\n    charSet := \"abcdedfghijklmnopqrst\"\n    var output strings.Builder\n    length := 10\n    for i := 0; i < length; i++ {\n        random := rand.Intn(len(charSet))\n        randomChar := charSet[random]\n        output.WriteString(string(randomChar))\n    }\n    fmt.Println(output.String())\n    output.Reset()\n\n    \/\/Lowercase and Uppercase Both\n    charSet = \"abcdedfghijklmnopqrstABCDEFGHIJKLMNOP\"\n    length = 20\n    for i := 0; i < length; i++ {\n        random := rand.Intn(len(charSet))\n        randomChar := charSet[random]\n        output.WriteString(string(randomChar))\n    }\n    fmt.Println(output.String())\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output:<\/strong><\/p>\n\n\n\n<p class=\"has-medium-font-size\">Below is the output on my machine. On your's it might give a different output<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">himsemkpkd\nnHaiEpccEdBfCFPtaBbi<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In above program we are using character set as<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">abcdedfghijklmnopqrst and abcdedfghijklmnopqrstABCDEFGHIJKLMNOP<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">All the above characters in charSet were ASCII characters hence we were able to index a character in <strong>charSet<\/strong> string. But this could be problem if the <strong>charSet<\/strong> contains non-ASCII character. <\/p>\n\n\n\n<p class=\"has-medium-font-size\">In Golang string is a sequence of bytes. A string literal actually represents a UTF-8 sequence of bytes. In UTF-8, ASCII characters are single-byte corresponding to the first 128 Unicode characters.&nbsp;All other characters are between 1 to 4 bytes. Due to this it is not possible to index a character in a string.&nbsp; In GO, rune data type represents a Unicode point.&nbsp; Once a string is converted to an array of rune then it is possible to index a character in that array of rune.<br><\/p>\n\n\n\n<p class=\"has-medium-font-size\">So in case, the character set contains some characters that are not ASCII they might occupy more than 1 bytes. In that case, we cannot use the above code to generate a random string as we cannot index into the charSet. For this case, we have to first convert a string into a rune array so that we can index into the rune array to the character and then incrementally form the random string. <\/p>\n\n\n\n<p class=\"has-medium-font-size\">As in the below example, our charSet contains a non-ASCII character <strong>'\u00a3'. <\/strong>This character occupies two bytes<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n    \"math\/rand\"\n    \"strings\"\n    \"time\"\n)\n\nfunc main() {\n    rand.Seed(time.Now().Unix())\n    \/\/Only lowercase and \u00a3\n    charSet := []rune(\"abcdedfghijklmnopqrst\u00a3\")\n    var output strings.Builder\n    length := 10\n    for i := 0; i < length; i++ {\n        random := rand.Intn(len(charSet))\n        randomChar := charSet[random]\n        output.WriteRune(randomChar)\n    }\n    fmt.Println(output.String())\n    output.Reset()\n \n   \/\/Lowercase and Uppercase Both and \u00a3\n    charSet = []rune(\"abcdedfghijklmnopqrstABCDEFGHIJKLMNOP\u00a3\")\n    length = 20\n    for i := 0; i < length; i++ {\n        random := rand.Intn(len(charSet))\n        randomChar := charSet[random]\n        output.WriteRune(randomChar)\n    }\n    fmt.Println(output.String())\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong>:<\/p>\n\n\n\n<p class=\"has-medium-font-size\">Below is the output on my machine. On yours it might give a different output<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">aidqpbse\u00a3j\nrebhjblsePsLpGBPOhfB<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Table of Contents OverviewCode Overview &#8216;mat\/rand&#8217; package of golang contains a Intn function that can be used to generate a pseudo-random number between [0,n). Bracket at the end means that n is&#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":[3,4,248,149],"class_list":["post-1947","post","type-post","status-publish","format-standard","hentry","category-tech","tag-go","tag-golang","tag-random","tag-string"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.7 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Generate a random string 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\/generate-random-string-golang\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Generate a random string in Go (Golang) - Welcome To Golang By Example\" \/>\n<meta property=\"og:description\" content=\"Table of Contents OverviewCode Overview &#8216;mat\/rand&#8217; package of golang contains a Intn function that can be used to generate a pseudo-random number between [0,n). 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