Go Program to Reverse a Number

Write a Go Program to Reverse a Number using for loop. The for loop condition make sure the number is greater than zero. Within the loop (for revnum > 0), 

• remainder = revnum % 10 – Assigning the last digit in a number to the remainder.
• reverse = reverse * 10 + remainder – Multiplies the reverse value with ten and adds the remainder value to it.
• revnum = revnum / 10 – Removes the last digit from the revnum

package main

import "fmt"

func main() {

    var revnum, remainder int

    fmt.Print("Enter the Number to Reverse = ")
    fmt.Scanln(&revnum)

    reverse := 0

    for revnum > 0 {
        remainder = revnum % 10
        reverse = reverse*10 + remainder
        revnum = revnum / 10
    }

    fmt.Println("The Reverse of the Given Number = ", reverse)
}

Go Program to Reverse a Number using Functions

package main

import "fmt"

func numberReverse(revnum int) int {
    var remainder int
    reverse := 0

    for ; revnum > 0; revnum = revnum / 10 {
        remainder = revnum % 10
        reverse = reverse*10 + remainder
    }
    return reverse
}
func main() {

    var revnum int

    fmt.Print("Enter the Number to Reverse = ")
    fmt.Scanln(&revnum)

    reverse := numberReverse(revnum)

    fmt.Println("The Reverse of the Given Number = ", reverse)
}

SureshMac:GoExamples suresh$ go run reversenum2.go
Enter the Number to Reverse = 3487
The Reverse of the Given Number =  7843
SureshMac:GoExamples suresh$ go run reversenum2.go
Enter the Number to Reverse = 90764
The Reverse of the Given Number =  46709

In this Golang example, we declared a recursive function to reverse the given number. Here, number_reverse (revnum / 10) calls the number_reverse() function recursively.

package main

import "fmt"

var reverse int = 0

func numberReverse(revnum int) int {

    var remainder int

    if revnum <= 0 {
        return 0

    }
    remainder = revnum % 10
    reverse = reverse*10 + remainder
    numberReverse(revnum / 10)
    return reverse
}
func main() {

    var revnum int

    fmt.Print("Enter the Number to Reverse = ")
    fmt.Scanln(&revnum)

    reverse := numberReverse(revnum)

    fmt.Println("The Reverse of the Given Number = ", reverse)
}

SureshMac:GoExamples suresh$ go run reversenum3.go
Enter the Number to Reverse = 3098
The Reverse of the Given Number =  8903
SureshMac:GoExamples suresh$ go run reversenum3.go
Enter the Number to Reverse = 390754
The Reverse of the Given Number =  457093