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How to Get Int63n Type Random Number in Golang?
• Last Updated : 26 Mar, 2020

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:

 `// 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:

 `// 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
```
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