Creating Simple Errors

Part of the Fundamentals section of Coddy's GO journey. Lesson 106 of 109.

In Go, you can create custom errors using the errors.New() function from the standard library.

Import the errors package:

import (
    "errors"
    "fmt"
)

Create a simple error with a message:

func divide(a, b int) (int, error) {
    if b == 0 {
        return 0, errors.New("cannot divide by zero")
    }
    return a / b, nil
}

func main() {
    result, err := divide(10, 0)
    if err != nil {
        fmt.Println("Error:", err)
    } else {
        fmt.Println("Result:", result)
    }
}

The output will be:

Error: cannot divide by zero

Challenge

Beginner

In this challenge, you'll practice creating a simple error in Go using the errors.New() function.

You have a function that checks if a username is valid. A username is considered valid if it has at least 5 characters. Your task is to complete the function by returning an appropriate error when the username is too short.

Try it yourself

package main

import (
	"errors"
	"fmt"
)

func main() {
	// Test with a valid username
	result, err := validateUsername("gopher123")
	if err != nil {
		fmt.Println("Error:", err)
	} else {
		fmt.Println(result)
	}

	// Test with an invalid username
	result, err = validateUsername("go")
	if err != nil {
		fmt.Println("Error:", err)
	} else {
		fmt.Println(result)
	}
}

func validateUsername(username string) (string, error) {
	if len(username) < 5 {
		// TODO: Return an error with the message "username must be at least 5 characters long"
		// Hint: Use errors.New() to create a new error
		return "", nil // Replace this line
	}
	return "Username is valid", nil
}