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
See also : Golang : Fix fmt.Scanf() on Windows will scan input twice problem
By Adam Ng
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