Overview

‘mat/rand’ package of golang contains a Intn function that can be used to generate a random number between [0,n). Bracket at the end means that n is exclusive.

To know more about what pseudo-random number means, checkout this post – /generate-random-number-golang

Below is the signature of this method. It takes input a number n and will return a number x in range 0<=x<n.

func Intn(n int) int

Above function can also be used to generate a random number in range a to b too. See below program. It is used to generate a number between range a to b. We are also providing a seed value to the rand so that it generates different output everytime.

Code

package main
import (
"fmt"
"math/rand"
"time"
)
func main() {
rand.Seed(time.Now().Unix())
//Generate a random number x where x is in range 5<=x<=20
rangeLower := 5
rangeUpper := 20
randomNum := rangeLower + rand.Intn(rangeUpper-rangeLower+1)
fmt.Println(randomNum)
//Generate a random number x where x is in range 100<=x<=200
rangeLower = 100
rangeUpper = 200
randomNum = rangeLower + rand.Intn(rangeUpper-rangeLower+1)
fmt.Println(randomNum)
}

Output:

Number between 5<=x<=20
Number between 100<=x<=200