How to Use Panic and Recover in Go: Simple Guide

In Go, use panic to stop normal execution when a serious error occurs, and recover inside a deferred function to regain control and handle the error gracefully. This combination helps prevent your program from crashing unexpectedly.

Syntax

panic stops the normal flow and starts panicking with a value, usually an error message.

recover is used inside a deferred function to catch the panic and resume normal execution.

Use defer to ensure recover runs when a panic happens.

go

func main() {
    defer func() {
        if r := recover(); r != nil {
            println("Recovered from panic:", r)
        }
    }()

    panic("something went wrong")
}

Output

Recovered from panic: something went wrong

Example

This example shows how panic stops the program and recover catches the panic to prevent the program from crashing.

go

package main

import "fmt"

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

    if b == 0 {
        panic("division by zero")
    }
    return a / b
}

func main() {
    fmt.Println("Result:", safeDivide(10, 2))
    fmt.Println("Result:", safeDivide(10, 0))
    fmt.Println("Program continues...")
}

Output

Result: 5
Recovered in safeDivide: division by zero
Result: 0
Program continues...

Common Pitfalls

• Calling recover outside a deferred function does nothing.
• If you don't use defer, recover won't catch the panic.
• Overusing panic for normal errors is bad practice; use error returns instead.

go

package main

import "fmt"

func wrongRecover() {
    r := recover() // This won't catch panic because it's not deferred
    fmt.Println("Recover called outside defer, got:", r)
}

func main() {
    wrongRecover()
    panic("panic without defer recover")
}

Quick Reference

Panic: Use to stop execution on serious errors.

Recover: Use inside defer to catch panic and continue.

Defer: Ensures recover runs after panic.

Function	Purpose	Usage
panic	Stops normal execution and starts panic	panic("error message")
recover	Catches panic inside deferred function	defer func() { if r := recover(); r != nil { /* handle */ } }()
defer	Delays function execution until surrounding function returns	defer func() { /* code */ }()

Key Takeaways

Use panic to stop execution when a serious error occurs.

Use recover inside a deferred function to catch and handle panics.

Always call recover within defer to successfully catch panics.

Avoid using panic for normal error handling; prefer error returns.

Recover lets your program continue running after a panic.