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Strings in Golang
  • Last Updated : 09 Aug, 2019
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In Go language, strings are different from other languages like Java, C++, Python, etc. it is a sequence of variable-width characters where each and every character is represented by one or more bytes using UTF-8 Encoding. Or in other words, strings are the immutable chain of arbitrary bytes(including bytes with zero value) or string is a read-only slice of bytes and the bytes of the strings can be represented in the Unicode text using UTF-8 encoding.
Due to UTF-8 encoding Golang string can contain a text which is the mixture of any language present in the world, without any confusion and limitation of the page. Generally, strings are enclosed in double-quotes””, as shown in the below example:

Example:




// Go program to illustrate
// how to create strings
package main
  
import "fmt"
  
func main() {
  
    // Creating and initializing a
    // variable with a string
    // Using shorthand declaration
    My_value_1 := "Welcome to GeeksforGeeks"
  
    // Using var keyword
    var My_value_2 string
    My_value_2 = "GeeksforGeeks"
  
    // Displaying strings
    fmt.Println("String 1: ", My_value_1)
    fmt.Println("String 2: ", My_value_2)
}

Output:

String 1:  Welcome to GeeksforGeeks
String 2:  GeeksforGeeks

Note: String can be empty, but they are not nil.

String Literals

In Go language, string literals are created in two different ways:



  • Using double quotes(“”): Here, the string literals are created using double-quotes(“”). This type of string support escape character as shown in the below table, but does not span multiple lines. This type of string literals is widely used in Golang programs.
    Escape characterDescription
    \\Backslash(\)
    \000Unicode character with the given 3-digit 8-bit octal code point
    \’Single quote (‘). It is only allowed inside character literals
    \”Double quote (“). It is only allowed inside interpreted string literals
    \aASCII bell (BEL)
    \bASCII backspace (BS)
    \fASCII formfeed (FF)
    \nASCII linefeed (LF
    \rASCII carriage return (CR)
    \tASCII tab (TAB)
    \uhhhhUnicode character with the given 4-digit 16-bit hex code point.
    Unicode character with the given 8-digit 32-bit hex code point.
    \vASCII vertical tab (VT)
    \xhhUnicode character with the given 2-digit 8-bit hex code point.
  • Using backticks(“): Here, the string literals are created using backticks(“) and also known as raw literals. Raw literals do not support escape characters, can span multiple lines, and may contain any character except backtick. It is, generally, used for writing multiple line message, in the regular expressions, and in HTML.

    Example:




    // Go program to illustrate string literals
    package main
      
    import "fmt"
      
    func main() {
      
        // Creating and initializing a
        // variable with a string literal
        // Using double-quote
        My_value_1 := "Welcome to GeeksforGeeks"
      
        // Adding escape character
        My_value_2 := "Welcome!\nGeeksforGeeks"
      
        // Using backticks
        My_value_3 := `Hello!GeeksforGeeks`
      
        // Adding escape character
        // in raw literals
        My_value_4 := `Hello!\nGeeksforGeeks`
      
        // Displaying strings
        fmt.Println("String 1: ", My_value_1)
        fmt.Println("String 2: ", My_value_2)
        fmt.Println("String 3: ", My_value_3)
        fmt.Println("String 4: ", My_value_4)
    }

    Output:

    String 1:  Welcome to GeeksforGeeks
    String 2:  Welcome!
    GeeksforGeeks
    String 3:  Hello!GeeksforGeeks
    String 4:  Hello!\nGeeksforGeeks
    

Important Points About String

  • Strings are immutable: In Go language, strings are immutable once a string is created the value of the string cannot be changed. Or in other words, strings are read-only. If you try to change, then the compiler will throw an error.

    Example:




    // Go program to illustrate
    // string are immutable
    package main
      
    import "fmt"
      
    // Main function
    func main() {
      
        // Creating and initializing a string
        // using shorthand declaration
        mystr := "Welcome to GeeksforGeeks"
      
        fmt.Println("String:", mystr)
      
        /* if you trying to change
              the value of the string
              then the compiler will
              throw an error, i.e,
             cannot assign to mystr[1]
      
           mystr[1]= 'G'
           fmt.Println("String:", mystr)
        */
      
    }

    Output:

    String: Welcome to GeeksforGeeks
  • How to iterate over a string?: You can iterate over string using for rang loop. This loop can iterate over the Unicode code point for a string.

    Syntax:

    for index, chr:= range str{
         // Statement..
    }
    

    Here, the index is the variable which store the first byte of UTF-8 encoded code point and chr store the characters of the given string and str is a string.

    Example:




    // Go program to illustrate how
    // to iterate over the string
    // using for range loop
    package main
      
    import "fmt"
      
    // Main function
    func main() {
      
        // String as a range in the for loop
        for index, s := range "GeeksForGeeKs" {
          
            fmt.Printf("The index number of %c is %d\n", s, index)
        }
    }

    Output:



    The index number of G is 0
    The index number of e is 1
    The index number of e is 2
    The index number of k is 3
    The index number of s is 4
    The index number of F is 5
    The index number of o is 6
    The index number of r is 7
    The index number of G is 8
    The index number of e is 9
    The index number of e is 10
    The index number of K is 11
    The index number of s is 12
    
  • How to access the individual byte of the string?: The string is of a byte so, we can access each byte of the given string.

    Example:




    // Go program to illustrate how to
    // access the bytes of the string
    package main
      
    import "fmt"
      
    // Main function
    func main() {
      
        // Creating and initializing a string
        str := "Welcome to GeeksforGeeks"
      
        // Accessing the bytes of the given string
        for c := 0; c < len(str); c++ {
      
            fmt.Printf("\nCharacter = %c Bytes = %v", str, str)
        }
    }

    Output:

    Character = W Bytes = 87
    Character = e Bytes = 101
    Character = l Bytes = 108
    Character = c Bytes = 99
    Character = o Bytes = 111
    Character = m Bytes = 109
    Character = e Bytes = 101
    Character =   Bytes = 32
    Character = t Bytes = 116
    Character = o Bytes = 111
    Character =   Bytes = 32
    Character = G Bytes = 71
    Character = e Bytes = 101
    Character = e Bytes = 101
    Character = k Bytes = 107
    Character = s Bytes = 115
    Character = f Bytes = 102
    Character = o Bytes = 111
    Character = r Bytes = 114
    Character = G Bytes = 71
    Character = e Bytes = 101
    Character = e Bytes = 101
    Character = k Bytes = 107
    Character = s Bytes = 115
    
  • How to create a string form the slice?: In Go language, you are allowed to create a string from the slice of bytes.

    Example:




    // Go program to illustrate how to
    // create a string from the slice
      
    package main
      
    import "fmt"
      
    // Main function
    func main() {
      
        // Creating and initializing a slice of byte
        myslice1 := []byte{0x47, 0x65, 0x65, 0x6b, 0x73}
      
        // Creating a string from the slice
        mystring1 := string(myslice1)
      
        // Displaying the string
        fmt.Println("String 1: ", mystring1)
      
        // Creating and initializing a slice of rune
        myslice2 := []rune{0x0047, 0x0065, 0x0065, 
                                   0x006b, 0x0073}
      
        // Creating a string from the slice
        mystring2 := string(myslice2)
      
        // Displaying the string
        fmt.Println("String 2: ", mystring2)
    }

    Output:

    String 1:  Geeks
    String 2:  Geeks
    
  • How to find the length of the string?: In Golang string, you can find the length of the string using two functions one is len() and another one is RuneCountInString(). The RuneCountInString() function is provided by UTF-8 package, this function returns the total number of rune presents in the string. And the len() function returns the number of bytes of the string.

    Example:




    // Go program to illustrate how to
    // find the length of the string
      
    package main
      
    import (
        "fmt"
        "unicode/utf8"
    )
      
    // Main function
    func main() {
      
        // Creating and initializing a string
        // using shorthand declaration
        mystr := "Welcome to GeeksforGeeks ??????"
      
        // Finding the length of the string
        // Using len() function
        length1 := len(mystr)
      
        // Using RuneCountInString() function
        length2 := utf8.RuneCountInString(mystr)
      
        // Displaying the length of the string
        fmt.Println("string:", mystr)
        fmt.Println("Length 1:", length1)
        fmt.Println("Length 2:", length2)
      
    }

    Output:

    string: Welcome to GeeksforGeeks ??????
    Length 1: 31
    Length 2: 31
    

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