Go for Beginners

Welcome to the world of Go! Whether you're just getting started or looking to refresh your knowledge, this guide will take you through the basics step by step.

Hello World

Let's kick things off with the classic "Hello, World!" program. Open your Go file and type:

package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}

This simple program prints the famous greeting to the console.

Variables

Go is statically typed, meaning you must declare the type of your variables. Here's an example:

package main

import "fmt"

func main() {
    x := 5
    var y int = 10
    z := x + y
    fmt.Printf("Sum: %d\n", z)
}

Learn how to declare variables and perform basic arithmetic operations.

Working With Strings

Strings in Go can be manipulated and combined. Explore string operations with this code:

package main

import "fmt"

func main() {
    greeting := "Hello"
    name := "World"
    message := fmt.Sprintf("%s, %s!", greeting, name)
    fmt.Println(message)
}

Working With Numbers

Perform operations on numbers in Go:

package main

import "fmt"

func main() {
    a := 5
    b := 2
    sum := a + b
    product := a * b
    fmt.Printf("Sum: %d, Product: %d\n", sum, product)
}

Getting Input From Users

Learn how to get user input with Go:

package main

import "fmt"

func main() {
    var name string
    fmt.Println("Enter your name:")
    fmt.Scanln(&name)
    fmt.Printf("Hello, %s!\n", name)
}

Arrays

Explore arrays in Go:

package main

import "fmt"

func main() {
    numbers := [5]int{1, 2, 3, 4, 5}
    for _, num := range numbers {
        fmt.Printf("Number: %d\n", num)
    }
}

Functions

Define functions and call them:

package main

import "fmt"

func add(x, y int) int {
    return x + y
}

func main() {
    result := add(3, 5)
    fmt.Printf("Sum: %d\n", result)
}

For Loop

Iterate through a range of numbers:

package main

import "fmt"

func main() {
    for i := 1; i <= 5; i++ {
        fmt.Printf("Number: %d\n", i)
    }
}

While Loop

Implement a simple while loop:

package main

import "fmt"

func main() {
    count := 0
    for count < 5 {
        fmt.Printf("Count: %d\n", count)
        count++
    }
}

Try / Except

Handle errors with Go's Result type:

package main

import (
    "fmt"
    "strconv"
)

func main() {
    num, err := strconv.Atoi("42")
    if err == nil {
        fmt.Printf("Parsed number: %d\n", num)
    } else {
        fmt.Println("Failed to parse")
    }
}

Reading Files

Read content from a file:

package main

import (
    "fmt"
    "io/ioutil"
)

func main() {
    content, err := ioutil.ReadFile("example.txt")
    if err == nil {
        fmt.Printf("File content: %s\n", content)
    } else {
        fmt.Println("Failed to read the file")
    }
}

Writing to Files

Write to a file in Go:

package main

import (
    "fmt"
    "io/ioutil"
)

func main() {
    data := []byte("Hello, Go!")
    err := ioutil.WriteFile("output.txt", data, 0644)
    if err != nil {
        fmt.Println("Failed to write to the file")
    }
}

Structs

Define a simple struct in Go:

package main

import "fmt"

type Dog struct {
    Name string
    Age  uint8
}

func main() {
    myDog := Dog{
        Name: "Buddy",
        Age:  3,
    }

    fmt.Printf("Dog's name: %s\n", myDog.Name)
    fmt.Printf("Dog's age: %d\n", myDog.Age)
}

Structs with Methods

While Go doesn't have traditional classes, you can achieve similar functionality with structs and methods:

package main

import "fmt"

type Dog struct {
    Name string
    Age  uint8
}

func NewDog(name string, age uint8) Dog {
    return Dog{
        Name: name,
        Age:  age,
    }
}

func (d Dog) Bark() {
    fmt.Printf("%s says woof!\n", d.Name)
}

func main() {
    myDog := NewDog("Buddy", 3)
    myDog.Bark()
}

Feel free to explore more of Go's powerful features as you continue your learning journey! Happy coding!

Practice Project

This simple Go project is designed for beginners to practice various language features. The program:

User Input:
- Receives the user's name and age through standard input.
Structs:
- Defines a Person struct to represent user data, including name and age.
Basic Math Operations:
- Performs basic mathematical operations (sum, product, and square) on the user's age.
Arrays:
- Stores the results of the mathematical operations in an array.
File I/O:
- Writes both user information and operation results to a file named output.txt.
Functions:
- Utilizes functions to modularize code for better organization and readability.

This project covers key Go concepts such as user input, structs, basic operations, arrays, file I/O, and functions. It serves as a practical hands-on exercise for those learning Go programming.

package main

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

type Person struct {
	Name string
	Age  uint8
}

func main() {
	fmt.Println("Enter your name:")
	var name string
	fmt.Scanln(&name)

	fmt.Println("Enter your age:")
	var ageInput string
	fmt.Scanln(&ageInput)
	age, err := strconv.ParseUint(ageInput, 10, 8)
	if err != nil {
		fmt.Println("Invalid age. Using 0 as default.")
		age = 0
	}

	user := Person{Name: name, Age: uint8(age)}

	resultArray := performOperations(user.Age)

	welcomeMessage(user)

	writeToFile(user, resultArray)
}

func welcomeMessage(person Person) {
	fmt.Printf("Welcome, %s! You are %d years old.\n", person.Name, person.Age)
}

func performOperations(age uint8) []uint8 {
	sum := age + 5
	product := age * 2
	square := age * age

	fmt.Printf("Age + 5: %d\n", sum)
	fmt.Printf("Age * 2: %d\n", product)
	fmt.Printf("Age squared: %d\n", square)

	return []uint8{sum, product, square}
}

func writeToFile(person Person, results []uint8) {
	file, err := os.Create("output.txt")
	if err != nil {
		fmt.Println("Failed to create the file")
		return
	}
	defer file.Close()

	file.WriteString(fmt.Sprintf("Name: %s\nAge: %d\n\n", person.Name, person.Age))
	file.WriteString("Results:\n")

	for index, result := range results {
		file.WriteString(fmt.Sprintf("Operation %d: %d\n", index+1, result))
	}

	fmt.Println("The information has been written to the 'output.txt' file.")
}

gusttavonl / go-for-beginners