The Errors Package

The Go standard library provides an "errors" package that makes it easy to deal with errors.

Read the godoc for the errors.New() function, but here's a simple example:

var err error = errors.New("something went wrong")

Assignment

Textio's software architects may have overcomplicated the requirements from the last coding assignment... oops. All we needed was a new generic error message that returns the string no dividing by 0 when a user attempts to get us to perform the taboo.

Complete the divide function. Use the errors.New() function to return an error when y == 0 that reads "no dividing by 0".

Remember that it's conventional to return the "zero" values of all other return values when you return a non-nil error in Go.

Solution

main.go

package main

import (
	"errors"
)

func divide(x, y float64) (float64, error) {
	if y == 0 {
		//Solution
		var err error = errors.New("no dividing by 0")
		return 0, err
		//
	}
	return x / y, nil
}

🧩 Understanding var err error = errors.New("no dividing by 0")

What’s happening

1. errors.New("no dividing by 0")

   • This creates a new error value with the message "no dividing by 0".

   • The errors package has a built-in function New() that returns an error object.

   Example:

   e := errors.New("something went wrong")
   fmt.Println(e) // prints: something went wrong

2. var err error

   • This declares a variable named err with the type error.

   • error is a built-in interface in Go that represents an error condition.

3. = errors.New("no dividing by 0")

   • This assigns the new error object you created to the variable err.

So together:

var err error = errors.New("no dividing by 0")

means:

“Make a variable called err, which is of type error, and store inside it a new error message that says no dividing by 0.”

---

How it’s used in context

if y == 0 {
	var err error = errors.New("no dividing by 0")
	return 0, err
}

• If someone tries to divide by zero, this creates an error value with a message.

• Then it returns that error instead of doing the math.

---

In plain English

• errors.New() = “Make me a simple error message.”

• var err error = ... = “Store that message inside a variable called err that represents an error.”

• return 0, err = “Return 0 for the result and this error to tell the caller something went wrong.”

---

Example Usage

result, err := divide(10, 0)
if err != nil {
	fmt.Println(err) // Output: no dividing by 0
} else {
	fmt.Println(result)
}

---

Quick Summary Table

Part	Meaning
errors.New("text")	Creates a new error with a message
var err error	Declares a variable of type error
err != nil	Checks if an error occurred
return 0, err	Returns an error instead of a valid result