Go Executor

Run and test Go code directly in the browser.

Version

Sample

💡 Go Basics Guide

1. Declaring Variables and Constants

Use var or := to declare variables. Use const for constants.

package main

var x int = 10
const Pi = 3.14

func main() {
    name := "Alice"
    isActive := true
    println(x, Pi, name, isActive)
}

2. Conditionals (if / switch)

Go supports if-else and switch statements with clean syntax.

x := 2
if x == 1 {
    println("One")
} else if x == 2 {
    println("Two")
} else {
    println("Other")
}

switch x {
case 1:
    println("One")
case 2:
    println("Two")
default:
    println("Other")
}

3. Loops

Go uses only the for loop, but it can act like a while loop.

for i := 0; i < 3; i++ {
    println(i)
}

n := 3
for n > 0 {
    println(n)
    n--
}

4. Arrays

Arrays have fixed size. Use slices for dynamic lists.

var nums = [3]int{10, 20, 30}
println(nums[1])

5. Slice Manipulation

Use slices and the built-in append, len, copy, and slicing syntax.

fruits := []string{"apple", "banana"}
fruits = append(fruits, "cherry")
fruits = fruits[1:]  // slice
println(len(fruits))

for _, fruit := range fruits {
    println(fruit)
}

6. Console Input/Output

Use fmt.Print, fmt.Scan, and fmt.Println.

import "fmt"

var name string
fmt.Print("Enter your name: ")
fmt.Scan(&name)
fmt.Println("Hello", name)

Go Basics Guide

7. Functions

Functions are declared with func and can return multiple values.

func greet(name string) string {
    return "Hello, " + name
}

message := greet("Alice")
println(message)

8. Maps

Maps are key-value stores. Declare with make().

ages := map[string]int{"Alice": 30}
ages["Bob"] = 25
println(ages["Alice"])

9. Error Handling

Go uses multiple return values for errors instead of exceptions.

import "errors"

func fail() error {
    return errors.New("something went wrong")
}

err := fail()
if err != nil {
    println(err.Error())
}

10. File I/O

Use os and io/ioutil packages to read/write files.

import (
  "fmt"
  "os"
  "io/ioutil"
)

ioutil.WriteFile("file.txt", []byte("Hello File"), 0644)

data, _ := ioutil.ReadFile("file.txt")
fmt.Println(string(data))

11. String Manipulation

Use the strings package for string operations.

import "strings"

text := "  Hello World  "
println(strings.TrimSpace(text))
println(strings.ToUpper(text))
println(strings.ReplaceAll(text, "Hello", "Hi"))

words := strings.Split(text, " ")
fmt.Println(words)

12. Structs & Objects

Use structs to define custom types with methods.

type Person struct {
  Name string
}

func (p Person) Greet() string {
  return "Hi, I'm " + p.Name
}

p := Person{Name: "Alice"}
println(p.Greet())

13. References (Pointers)

Go supports pointers using * and &.

x := 10
ptr := &x
*ptr = 20
println(x) // 20