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Intermediate 16 min readModule: Module 5: Functions, Multiple Returns & Named Returns

Multiple Return Values & The 'defer' Statement

Return multiple values (result, error) and guarantee resource cleanup with LIFO 'defer' statements.

What You Will Learn in This Lesson

  • Functions returning multiple values (value, error)
  • The 'defer' statement for guaranteed cleanup before function exit
  • LIFO (Last In, First Out) execution order of multiple defers

Introduction & Core Concept

Go functions can return any number of results. The 'defer' keyword schedules a function call to run immediately before the enclosing function returns.
WHY DOES THIS MATTER IN THE REAL WORLD?

Placing 'defer file.Close()' immediately after opening a file guarantees the file descriptor closes, preventing leaks.

Multiple Returns & Defer Cleanup

go
go
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package main
import "fmt"
 
func divide(a, b float64) (float64, error) {
    if b == 0 {
        return 0, fmt.Errorf("division by zero")
    }
    return a / b, nil
}
 
func main() {
    defer fmt.Println("Cleanup: Execution completed.")
    res, err := divide(100, 4)
    if err == nil {
        fmt.Println("Result:", res)
    }
}

Line-by-Line Technical Breakdown

1Defer statements evaluate their arguments immediately when encountered.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[GO]
GO SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Always pair resource acquisition (opening files/locks) with an immediate defer cleanup.

Lesson Summary & Core Takeaways

  • Multiple returns and defer make resource management explicit and clean.