GO Program to Find Factorial of a Number

This program takes a positive integer from the user and computes factorial using for loop. New function factorial created which returns the factorial value of a number.


//Program to find Factorial of number
package main
import "fmt"

/* Variable Declaration */
var factVal uint64 = 1 // uint64 is the set of all unsigned 64-bit integers.
                       // Range: 0 through 18446744073709551615. 
var i int = 1
var n int

/*     function declaration        */
func factorial(n int) uint64 {   
    if(n < 0){
        fmt.Print("Factorial of negative number doesn't exist.")    
        for i:=1; i<=n; i++ {
            factVal *= uint64(i)  // mismatched types int64 and int
    return factVal  /* return from function*/

func main(){    
    fmt.Print("Enter a positive integer between 0 - 50 : ")
    fmt.Print("Factorial is: ",factorial(n))
In above program we have created a function "factorial" which returns a value of uint64.

factVal *= uint64(i) // i is int and factVal is uint64. Compiler will through exception "mismatched types int64 and int" if we not convert i to uint64.
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