{"id":1800,"date":"2020-03-25T14:32:36","date_gmt":"2020-03-25T14:32:36","guid":{"rendered":"https:\/\/golangbyexamples.com\/?p=1800"},"modified":"2020-03-29T10:26:11","modified_gmt":"2020-03-29T10:26:11","slug":"number-characters-string-golang","status":"publish","type":"post","link":"https:\/\/golangbyexamples.com\/number-characters-string-golang\/","title":{"rendered":"Number of Characters or length of a string in Go (Golang)"},"content":{"rendered":"\n

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. All other characters are between 1 -4 bytes. That is why it is not possible to get the exact length of the string using the built-in len<\/strong> function of go. It might work if the string only contains ASCII characters. But if the string contains Non-ASCII characters then it will give the correct output.<\/p>\n\n\n\n

 For example, see below the program and its output. \u00a3<\/strong> in the string below is a Non-ASCII character.<\/p>\n\n\n\n

package main\n\nimport \"fmt\"\n\nfunc main() {\n    sample := \"ab\u00a3c\"\n    for i := 0; i < 4; i++ {\n        fmt.Printf(\"%c\\n\", sample[i])\n    }\n    fmt.Printf(\"Length is %d\\n\", len(sample))\n}<\/code><\/pre>\n\n\n\n
Output:<\/strong><\/p>\n\n\n\n
a\nb\n\u00c2\n\u00a3\nLength is 5<\/code><\/pre>\n\n\n\n
As you might have noticed , it prints different characters than expected and length is also 5 instead of 4. Why is that? To answer please remember we said that a string is essentially a slice of bytes. Let's print that slice of bytes using<\/p>\n\n\n\n
sample := \"ab\u00a3c\"\nfmt.Println([]byte(sample))<\/code><\/pre>\n\n\n\n
Output will be<\/p>\n\n\n\n
[97 98 194 163 99]<\/code><\/pre>\n\n\n\n
This is the mapping of each of character to its byte sequence. As you can notice a<\/strong>, b<\/strong>, c<\/strong> take each 1 byte but \u00a3<\/strong> takes two bytes. That is why the length of the string is 5 and not 4<\/p>\n\n\n\n
a<\/td>97<\/td><\/tr>
b<\/td>98<\/td><\/tr>
\u00a3<\/td>194, 163<\/td><\/tr>
c<\/td>99<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
There are two alternatives to get the correct length of a string<\/p>\n\n\n\n
  • Using rune data type . rune<\/strong> data type represents a Unicode point.  Once a string is converted to an array of rune<\/strong> then it is possible to get the correct length of a string.<\/li><\/ul>\n\n\n\n
    • Using range operator over the string and calculating the length. range operator iterates over the UTF-8 characters in a string.<\/li><\/ul>\n\n\n\n
      The below code illustrates the above two points.<\/p>\n\n\n\n
      package main\n\nimport \"fmt\"\n\nfunc main() {\n    sample := \"ab\u00a3c\"\n    \/\/Using rune\n    s := []rune(sample)\n    fmt.Println(len(s))\n    \n    \/\/Using range\n    len := 0\n    for range sample {\n        len++\n    }\n    fmt.Println(len)\n}<\/code><\/pre>\n\n\n\n
      Output:<\/strong><\/p>\n\n\n\n
      4\n4<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
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