String literals in Golang.

From previous articles, we know that strings in Golang are contained in between double quotes " " , but if we try to write on next line or write a multiline string. We may break the syntax or identations used in Go language. You may have tried to use Python's method ("""string"""), but that will again break Golang's syntax:

multilineString := """line 1
line 2
line 3"""

Let's dive deeper into string literals in Golang and find out different ways to write multiline strings withing Golang.

What is a String literal in Go language?

A string literal in Go language represents a string constant obtained from concatenating a sequence of characters.

There are two forms of string literals in Go language: raw string literals and interpreted string literals.

1. Raw string literals are every character sequence included between back quotes `foo`(Keyboard location: below ESC key), where foo could be anything but should not contain a back quote. For python programmers, `foo` in Golang is the same as """foo""" in Python. The characters between back quotes will be treated as raw strings. Eg. A carriage return (\r) or line break (\n) will not be treated speacially. The value of a raw string literal is the string composed of the uninterpreted (implicitly UTF-8-encoded) characters; in particular, backslashes have no special meaning.

2. Interpreted string literals are character sequences between double quotes, as in "bar" where the bar could be anything except new line character or a double quote. But you can use rune literals to add a double as pard of bar with a backslash as \". You can introduce characters of different encodings.

How to write multiline string in Go language?

• Using raw string Literals - you can use multiline strings delimited by back ticks (`). (only new lines between back quotes will be considered as new line.)

  • `line 1
    line 2
        line 3
    line #$(* 4`

  • Also, special characters are not trated exceptionally,

  • package main
    
    import (
        "fmt"
    )
    
    func main(){
        multiLine := `line 1
    line 2 \n
    line 3 \n
    line 4`
    
        fmt.Print(multiline)
    }
    

  • 
    line 1
    line 2 \n
    line 3 \n
    line 4
    Program exited.

• Using interpreted string literals - As we know that special character delimited between double quotes are interpreted to have special meaning.

  • "line 1 \nline2 \n  line3 \nline4"

  • 
    line 1
    line2
    line3
    line4

  • So, we use string concatenation to make it more readable.

  • package main
    
    import (
    	"fmt"
    )
    
    func main() {
    	multiline := "line 1 \n" +
    		"line2 \n" +
    		"  line3 \n" +
    		"line4"
    
    	fmt.Print(multiline)
    }
    

  • 
    line 1
    line2
    line3
    line4

How to convert a raw string literal to interpreted string literal?

For example, printing this raw string literal gives

func main() {
    s := `\033[1mString.\033[0m`
    println(s)
}

\033[1mString.\033[0m

but we want the same result like when we use interpreted string literals.

func main() {
    s := "\033[1mString.\033[0m"
    println(s) 
}

String.

So, we need to change raw string literal to interpreted string literal. We may follow use these steps:

• Import strconv package from Go language's standard library.

• import (
      "fmt"
      "strconv"
  )

• And then use strconv.Unquote() function.

The string value passed to strconv.Unquote() must contain wrapping double quotes or backticks, and since the source s does not contain the wrapping quotes. i.e, `"` + s + `"`

• func main() {
      s := `\033[1mString in bold.\033[0m`
  
      sInterpreted, err := strconv.Unquote(`"` + s + `"`)
      if err != nil {
          panic(err)
      }
  }

Finally, We have this working script.

package main

import(
    "fmt"
    "strconv"
)

func main() {
    s := `\033[1mString in bold.\033[0m`

    sInterpreted, err := strconv.Unquote(`"` + s + `"`)
    if err != nil {
        panic(err)
    }
    fmt.Println(sInterpreted)
}

String.

Conclusion

In this tutorial, we learnt about string literals in Golang. there are two type of string literals; Raw string literal and Interpreted string literal.