Clean-up with Defer

Snippet

Clean-up with Defer

The `defer` keyword schedules a function call to execute when the surrounding function returns. This is essential for cleanup tasks like closing files or releasing resources. Deferred functions execute in Last-In-First-Out order - the last defer runs first when the function exits. This ensures resources are always released even if an error occurs mid-function.

snippet.go
go
package main
 
import (
    "fmt"
    "os"
)
 
func readFile(name string) error {
    file, err := os.Open(name)
    if err != nil {
        return err
    }
    defer file.Close()
 
    buffer := make([]byte, 1024)
    _, err = file.Read(buffer)
    return err
}
 
func main() {
    defer fmt.Println("Last")
    defer fmt.Println("Second")
    fmt.Println("First")
}

Breakdown

defer file.Close()

Schedules file.Close() to run when function exits

make([]byte, 1024)

Creates a buffer for reading file contents

defer fmt.Println("Last")

Deferred - runs after surrounding function returns

defer fmt.Println("Second")

Second defer - runs before "Last" due to LIFO order

fmt.Println("First")

Executed immediately, then defers run on exit

Previous snippet Next snippet

More Beginner Go exercises →

From your library

Clean-up with Defer

Related