Returning errors in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the common way to return errors in Go functions?

In Go, functions often return an error as the last return value. If there is no error, the error value is nil.

beginner

How do you check if a function returned an error in Go?

You compare the returned error value to nil. If it is not nil, an error occurred and should be handled.

intermediate

What does the following Go code return?

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

This function returns the result of a divided by b and nil error if b is not zero. If b is zero, it returns 0 and an error with the message "cannot divide by zero".

intermediate

Why is it useful to return errors instead of panicking in Go?

Returning errors allows the caller to decide how to handle the problem, making the program more robust and easier to maintain.

beginner

What package is commonly used to create error values in Go?

The fmt package is commonly used with fmt.Errorf to create formatted error messages.

In Go, what does a function usually return to indicate an error?

A An error value as the last return value

B A boolean true or false

C A panic message

D A string describing the error

Go functions typically return an error type as the last return value to indicate if an error occurred.

How do you check if a Go function returned an error?

A Check if error is true

B Check if error equals zero

C Check if error is nil

D Check if error is empty string

In Go, an error is nil if no error occurred. If it is not nil, an error happened.

What does fmt.Errorf do in Go?

A Creates a formatted error value

B Prints an error message

C Stops the program

D Returns a boolean

fmt.Errorf creates an error value with a formatted message.

What should you do if a Go function returns a non-nil error?

A Return nil

B Ignore it

C Always panic

D Handle the error appropriately

You should handle errors to keep your program stable and predictable.

Which of these is a correct function signature for returning an error in Go?

A func example() error int

B func example() (int, error)

C func example() error

D func example() int error

The correct syntax places error as the last return type: (int, error).

Explain how to return and check errors in a Go function.

Think about how Go functions signal problems and how callers respond.

Describe why returning errors is preferred over panicking in Go programs.

Consider the difference between stopping a program and letting it recover.