How to Get Int63n Type Random Number in Golang?

Go language provides inbuilt support for generating random numbers of the specified type with the help of a math/rand package. This package implements pseudo-random number generators. These random numbers are generated by a source and this source produces a deterministic sequence of values every time when the program run. And if you want to random numbers for security-sensitive work, then use the crypto/rand package. You are allowed to generate a non-negative pseudo-random number in [0, n) of 63-bit integer n as an int64 type from the default source with the help of the Int63n() function provided by the math/rand package. So, you need to add a math/rand package in your program with the help of the import keyword to access the Int63n() function. This method will panic if the value of n is <= 0. Syntax:

func Int63n(n int64) int64

Let us discuss this concept with the help of the given examples: Example 1: C

// Golang program to illustrate how to
// get int63n type random number
package main

import (
    "fmt"
    "math/rand"
)

// Main function
func main() {

    // Finding random numbers of int63n type
    // Using Int63n() function
    res_1 := rand.Int63n(7)
    res_2 := rand.Int63n(3)
    res_3 := rand.Int63n(1)

    // Displaying the result
    fmt.Println("Random Number 1: ", res_1)
    fmt.Println("Random Number 2: ", res_2)
    fmt.Println("Random Number 3: ", res_3)
}

Output:

Random Number 1:  5
Random Number 2:  1
Random Number 3:  0

Example 2: C

// Golang program to illustrate how to
// get int63n type random number
package main

import (
    "fmt"
    "math/rand"
)

// Function
func int63nrandom(value_1, value_2 int64) int64 {
    return value_1 + value_2 + rand.Int63n(4)

}

// Main function
func main() {

    // Getting result from Int63nrandom() function
    res1 := int63nrandom(10, 3)
    res2 := int63nrandom(430, 56)
    res3 := int63nrandom(13, 500)

    // Displaying results
    fmt.Println("Result 1: ", res1)
    fmt.Println("Result 2: ", res2)
    fmt.Println("Result 3: ", res3)
}

Output:

Result 1:  15
Result 2:  489
Result 3:  514