Go Program to Find Factorial of a Number

Write a Go Program to Find factorial of a Number using For loop. The for loop (for i := 1; i <= factorialnum; i++) iteration starts at one and ends at user given value. Within the loop (factorial = factorial * i), we multiply each value with a factorial variable value.

package main

import "fmt"

func main() {

    var factorialnum, factorial int
    factorial = 1

    fmt.Print("Enter any Number to find the Factorial = ")
    fmt.Scanln(&factorialnum)

    for i := 1; i <= factorialnum; i++ {
        factorial = factorial * i
    }
    fmt.Println("The Factorial of ", factorialnum, " = ", factorial)
}

Go Program to Find factorial of a Number using Functions

In this example, we created a separate function (calcFactorial (factorialnum int)) that returns the factorial of the user given number.

package main

import "fmt"

var factorial int

func calcFactorial(factorialnum int) int {
    factorial = 1
    for i := 1; i <= factorialnum; i++ {
        factorial = factorial * i
    }
    return factorial
}
func main() {

    var factorialnum int

    fmt.Print("Enter any Number to find the Factorial = ")
    fmt.Scanln(&factorialnum)

    factorial = calcFactorial(factorialnum)
    fmt.Println("The Factorial of ", factorialnum, " = ", factorial)
}

Enter any Number to find the Factorial = 9
The Factorial of  9  =  362880

In this Golang program, we created a recursive function that returns the factorial of a number.

package main

import "fmt"

var factorial int

func calcFactorial(factorialnum int) int {
    if factorialnum == 0 || factorialnum == 1 {
        return 1
    } else {
        return factorialnum * calcFactorial(factorialnum-1)
    }
}
func main() {

    var factorialnum int

    fmt.Print("Enter any Number to find the Factorial = ")
    fmt.Scanln(&factorialnum)

    factorial = calcFactorial(factorialnum)
    fmt.Println("The Factorial of ", factorialnum, " = ", factorial)
}

Enter any Number to find the Factorial = 4
The Factorial of  4  =  24

This factorial of a Number program uses the Pointers concept to achieve the results.

package main

import "fmt"

func main() {

    var factorialnum, factorial int
    var nw *int
    factorial = 1

    fmt.Print("Enter any Number to find the Factorial = ")
    fmt.Scanln(&factorialnum)

    nw = &factorialnum

    for i := 1; i <= *nw; i++ {
        factorial = factorial * i
    }
    fmt.Println("The Factorial of ", factorialnum, " using Normal  = ", factorial)
    fmt.Println("The Factorial of ", *nw, " using Pointers = ", factorial)
}

Enter any Number to find the Factorial = 6
The Factorial of  6  using Normal  =  720
The Factorial of  6  using Pointers =  720

The Factorial of a Number example using Call by Reference.

package main

import "fmt"

var factorial int

func calcFactorial(factnum *int) int {
    factorial = 1
    for i := 1; i <= *factnum; i++ {
        factorial = factorial * i
    }
    return factorial
}
func main() {

    var factorialnum int

    fmt.Print("Enter any Number to find the Factorial = ")
    fmt.Scanln(&factorialnum)

    factorial = calcFactorial(&factorialnum)
    fmt.Println("The Factorial of ", factorialnum, " = ", factorial)
}

Enter any Number to find the Factorial = 7
The Factorial of  7  =  5040