How to Create Function in Go: Syntax and Examples

In Go, you create a function using the func keyword followed by the function name, parameters in parentheses, and the function body in braces. Functions can return values by specifying return types after the parameters.

Syntax

The basic syntax to create a function in Go is:

• func: keyword to declare a function.
• functionName: the name you give your function.
• parameters: inputs inside parentheses, each with a name and type.
• return type: optional, specifies the type of value the function returns.
• function body: code inside curly braces that runs when the function is called.

go

func functionName(parameterName parameterType) returnType {
    // function body
}

Example

This example shows a function named add that takes two integers and returns their sum.

go

package main

import "fmt"

func add(a int, b int) int {
    return a + b
}

func main() {
    result := add(3, 5)
    fmt.Println("Sum:", result)
}

Output

Sum: 8

Common Pitfalls

Common mistakes when creating functions in Go include:

• Forgetting to specify parameter types.
• Not returning a value when the function signature requires one.
• Using the wrong return type or mismatched return statements.
• Not calling the function after defining it.

go

package main

import "fmt"

// Wrong: missing parameter types
// func greet(name) {
//     fmt.Println("Hello", name)
// }

// Correct:
func greet(name string) {
    fmt.Println("Hello", name)
}

func main() {
    greet("Alice")
}

Output

Hello Alice

Quick Reference

Part	Description	Example
func	Keyword to declare a function	func
functionName	Name of the function	add
parameters	Input variables with types	a int, b int
return type	Type of value returned	int
function body	Code inside braces	{ return a + b }

Key Takeaways

Use the func keyword followed by the function name and parameters to create a function in Go.

Always specify parameter types and return types if your function returns a value.

The function body contains the code that runs when the function is called.

Common errors include missing parameter types and mismatched return statements.

Call your function in main or other functions to execute its code.