Recover usage in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the recover function in Go?

recover is used to regain control of a panicking goroutine. It allows a program to handle a panic and continue running instead of crashing.

beginner

Where must recover be called to successfully catch a panic?

recover must be called inside a deferred function. If called outside a deferred function, it will not stop the panic.

beginner

What happens if recover is called and there is no panic?

If recover is called when there is no panic, it returns nil and does nothing else.

intermediate

Explain the relationship between panic, defer, and recover in Go.

panic stops normal execution and starts panicking. defer functions run even during panic. Inside a deferred function, recover can catch the panic and stop the program from crashing.

beginner

Show a simple Go code snippet that uses recover to handle a panic.

func safeDivide(a, b int) int {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("Recovered from panic:", r)
        }
    }()
    return a / b
}

What does recover return when called during a panic?

A Boolean true

B The value passed to panic

C An error object

D Always nil

recover returns the value passed to panic if called during a panic.

Where should recover be placed to catch a panic?

A Inside a deferred function

B Anywhere in the code

C Inside the main function only

D Inside a goroutine only

recover only works inside a deferred function.

What happens if a panic is not recovered?

A Program crashes and prints stack trace

B Program continues normally

C Program silently ignores panic

D Program restarts automatically

If panic is not recovered, the program crashes and prints a stack trace.

Which keyword is used to delay execution of a function until the surrounding function returns?

A recover

B panic

C defer

D go

defer delays execution of a function until the surrounding function returns.

Can recover stop a panic if called outside a deferred function?

A Yes, always

B Only if panic is recent

C Only inside main function

D No, it returns nil and does nothing

recover only stops panic if called inside a deferred function; otherwise, it returns nil.

Describe how to use recover to handle a panic in Go.

Think about how defer and recover work together.

Explain the flow of a Go program when a panic occurs and is recovered.

Focus on panic, defer, and recover sequence.