Strings in Golang

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:

C

// 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. 

.golang-string-table { border-collapse: collapse; width: 100%; } .golang-string-table td { border: 1px solid #5fb962; text-align: left !important; padding: 8px; } .golang-string-table th { border: 1px solid #5fb962; padding: 8px; } .golang-string-table tr>th{ background-color: #c6ebd9; vertical-align: middle; } .golang-string-table tr:nth-child(odd) { background-color: #ffffff; } 

Escape character	Description
\\	Backslash(\)
\000	Unicode 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
\a	ASCII bell (BEL)
\b	ASCII backspace (BS)
\f	ASCII formfeed (FF)
\n	ASCII linefeed (LF
\r	ASCII carriage return (CR)
\t	ASCII tab (TAB)
\uhhhh	Unicode character with the given 4-digit 16-bit hex code point.
	Unicode character with the given 8-digit 32-bit hex code point.
\v	ASCII vertical tab (VT)
\xhh	Unicode 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:

C

// 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:

C

// 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 range 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:

C

// 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:

C

// 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:

C

// 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:

C

// 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