Replace Characters in a Golang String

The strings package of Golang has a Replace() function which we can use to replace some characters in a string with a new value. It replaces only a specified "n" occurrences of the substring.

In addition to Replace(), there is a ReplaceAll() function that replaces all the occurrences of a given substring with a new value.

Syntax

func Replace(s, old, new string, n int) string

Where,

• s is the given string

• old is the string which we want to replace

• new is the string which will replace the old string

• n represents the number of characters which we want to replace in the given string.

Example

The following example demonstrates how you can use the Replace() function to replace a substring with a new string.

package main
import (
   "fmt"
   "strings"
)
func main() {

   // Initializing the Strings
   s := "Go Programming Language"
   old := "Go"
   newstring := "Golang"
   n := 1

   // Display the Strings
   fmt.Println("Original String: ", s)

   // Using the Replace Function
   testresult := strings.Replace(s, old, newstring, n)

   // Display the Replace Output
   fmt.Println("Replace Go with Golang:", testresult)
}

Output

It will generate the following output −

Original String: Go Programming Language
Replace Go with Golang: Golang Programming Language

Example

In this example, we are going to see how to replace a single character with a new value at a particular defined postion or index.

package main
import (
   "fmt"
   "strings"
)
func main() {
   
   // Initializing the Strings
   x := "Replace String Function"
   y := "Go Language"

   // Display the Strings
   fmt.Println("1st String:", x)
   fmt.Println("2nd String:", y)

   // Using the Replace Function
   test1 := strings.Replace(x, "i", "I", 2)
   test2 := strings.Replace(y, "g", "G", -1)

   // Display the Replace Output
   fmt.Println("\n Replace 'i' with 'I' in the 1st String: \n", test1)
   fmt.Println("\n Replace 'g' with 'G' in the 2nd String: \n", test2)
}

Output

It will generate the following output −

1st String: Replace String Function
2nd String: Go Language

Replace 'i' with 'I' in the 1st String:
Replace StrIng FunctIon

Replace 'g' with 'G' in the 2nd String:
Go LanGuaGe