How to use strings.Replace() in Golang

The Golang strings.Replace() method

The Go programming language, or Golang, provides a string package that contains various functions for manipulating UTF-8 encoded strings.

One of these functions is the Replace() method.

In Golang, the strings.Replace() function returns a copy of the given string, with the first n non-overlapping instances of the old string replaced with the new one.

Syntax

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

Parameter

  • s: This is the given string.
  • old: This is the string to be replaced.
  • new: This is the string that replaces the old one.
  • n: This is the number of times the old string is replaced.

Note: If the old string is empty, it matches at the start of the string. After each UTF-8 sequence, it yields up to k+1 replacements, giving a k-rune string. There is no limit to how many replacements can be made if n is less than zero.

To use the string package’s functions, we must use the import keyword to import a string package into our program.

package main
  
import (
    "fmt"
    "strings"
)

Code

The following code shows how to implement the strings.Replace() method in Golang.

// Golang program 
// Strings.Replace() function
  
package main
  // Accessing the string package's function
import (
    "fmt"
    "strings"
)
  
func main() {
    // Using the Replace() function
    //Replacing the first 3 matched substring m with M
    fmt.Println(strings.Replace("my name is maria marris", "m", "M", 3))
    //Replacing every matched substring j with J
    fmt.Println(strings.Replace("john joe job jona jonathan", "j", "J", -1))
}

What happens if we omit the old parameter?

Let’s now take a look at another example without the old value.

// Golang program 
// Using the strings.Replace() function without the old parameter 
  
package main
  
import (
    "fmt"
    "strings"
)
  
func main() {
  
    // Using the function
    fmt.Println(strings.Replace("my name is maria marris", "", "M", 3))
    fmt.Println(strings.Replace("john joe job jona jonathan", "", "J", -1))
}

Explanation

In the above code, every alternate position is replaced n times by the new string.

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