Creating Formatted Errors

Part of the Fundamentals section of Coddy's GO journey. Lesson 107 of 109.

Creating Formatted Errors... allows you to include dynamic values in error messages.

The fmt.Errorf() function creates errors with formatted strings, similar to fmt.Printf():

import (
    "fmt"
)

func divide(a, b int) (int, error) {
    if b == 0 {
        return 0, fmt.Errorf("cannot divide %d by zero", a)
    }
    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 10 by zero

Challenge

Beginner

In this challenge, you'll practice creating formatted error messages using the fmt.Errorf function. You have a program that validates a username, and you need to create a proper error message when the username is invalid.

The program has a predefined username that's too short (less than 5 characters). Your task is to create a formatted error message that includes the invalid username and the minimum required length.

Try it yourself

package main

import (
	"fmt"
)

func main() {
	// Predefined username that's too short
	username := "bob"
	// Minimum required length
	minLength := 5
	
	// Check if username is valid
	if len(username) < minLength {
		// TODO: Create a formatted error using fmt.Errorf that includes:
		// 1. The invalid username
		// 2. The minimum required length
		// Example format: "invalid username: [username] is too short, minimum length is [minLength]"
		err := // Your code here
		
		// Print the error
		fmt.Println(err)
	} else {
		fmt.Println("Username is valid!")
	}
}