Golang : Number guessing game with user input verification example

Helping a Golang student from Mexico. She is building a simple random number guessing game and she wants to know how to check the user input to determine if the user input is indeed an integer value.

Simple, use the strconv.ParseInt() to parse the user input and if the error != nil, then we know the user input is not integer

For example,

 userNumber, err := strconv.ParseInt(userInput, 10, 0)
 if err != nil {
 fmt.Println("You must enter an integer value.")
 }

The full program. Here you go!

 package main

 import (
 "fmt"
 "math/rand"
 "strconv"
 "time"
 )

 var (
 userInput string
 attempts  int = 0
 )

 // https://www.socketloop.com/tutorials/golang-random-integer-with-rand-seed-within-a-given-range
 func numRandom(min, max int) int {
 rand.Seed(time.Now().Unix())
 return rand.Intn(max-min) + min
 }

 func main() {
 numberToGuess := numRandom(1, 10)
 //fmt.Println(numberToGuess)

 for {
 attempts++
 fmt.Println("A number is generated between 1 to 10. What do you think the number is: ")

 // see https://www.socketloop.com/tutorials/golang-fix-fmt-scanf-on-windows-will-scan-input-twice-problem
 // for scanf under Windows OS
 fmt.Scanf("%v\n", &userInput)

 // check if userinput is integer
 userNumber, err := strconv.ParseInt(userInput, 10, 0)
 if err != nil {
 fmt.Println("You must enter an integer value.")
 } else if numberToGuess == int(userNumber) {
 break
 } else if int(userNumber) < numberToGuess {
 fmt.Printf("Smaller than the number. Try again\n")
 } else {
 fmt.Printf("Larger than the number. Try again\n")
 }
 }
 fmt.Printf("Yup, the number is %v. You guessed it correctly after %v attempts\n", numberToGuess, attempts)

 }

Sample output:

A number is generated between 1 to 10. What do you think the number is:

2

Larger than the number. Try again

A number is generated between 1 to 10. What do you think the number is:

1

Yup, the number is 1. You guessed it correctly after 2 attempts

Happy coding!

References:

https://www.socketloop.com/tutorials/golang-fix-fmt-scanf-on-windows-will-scan-input-twice-problem

https://www.socketloop.com/tutorials/golang-random-integer-with-rand-seed-within-a-given-range