Ruby expert learned the basic grammar of Go language

Overview

Six months after learning Ruby, I wanted to learn another language, so I touched Go a little.

Difference between Ruby and Go (FizzBuzz)

When solving the FizzBuzz problem with Ruby, there are various ways to write it, such as for, while, but this time I wrote it with the times method.

fizzbuzz.rb

1..100.times do |i|
    if i%15==0
        puts "FizzBuzz"
    elsif i%3==0
        puts "Fizz"
    elsif i%5==0 
        puts "Buzz"
    else
        puts i
    end
end

When written in Go, it became as follows.

fizzbuzz.go

package main

import (
	"fmt"
)

func main() {
	for i := 0; i < 100; i++ {
		if i%5 == 0 && i%3 == 0 {
			fmt.Println("Fizz Buzz")
		} else if i%3 == 0 {
			fmt.Println("Fizz")
		} else if i%5 == 0 {
			fmt.Println("Buzz")
		} else {
			fmt.Println(i)
		}
	}
}

There were some differences compared to Ruby even if I made a simple program, so I tried to summarize it myself.

--About package --About import --About iterative processing -About: =

package

In Go, programming elements belong to some kind of package, and you must declare the package. When I created an empty file and ran go run test.go, I got an error such as ʻexpected'package', found'EOF'`.

Therefore, if there is no package or main function as shown in the code below, an error will occur at runtime.

test.go

package main

func main() {

}

import In Go, if you use a function that is not written in the main package, you must describe the package name that has that function. This is an image like the standard library in the Ruby library.

For Ruby

standard_library.rb

require 'Time'
p Time.strptime('2020-03-21T01:58:30+09:00', '%Y-%m-%dT%H:%M:%S%z') 
# -> 2020-03-21 01:58:30 +0900

For Go

hello.go

package main
import("fmt")


func main() {
	fmt.Println("Hello World")
	// -> Hello World
}

Iterative processing

In Ruby, there are various ways to write for, while, times, etc. when performing iterative processing. In Go, only for statement is used for iterative processing.

However, it is also possible to write like foreach as shown below.

foreach.go

package main

import (
	"fmt"
)

func main() {
	fruits := map[string]string{
		"apple": "Apple",
		"banana": "banana",
		"pineapple": "pineapple",
	}
	for key, value := range fruits {
		fmt.Println("key:", key, " value:", value)
	}
}

// key: apple  value:Apple
// key: banana  value:banana
// key: pineapple  value:pineapple

About: =

When explicitly defining a variable with go, describe as follows.

variable.go

package main

import ("fmt")

func main() {
	var x,y,z int
	x = 1
	y = 2
	z = 3

	fmt.Println(x)
	fmt.Println(y)
	fmt.Println(z)
}

// 1
// 2
// 3

However, it is also possible to implicitly define a variable, in which case it will be as follows.

variable.go

package main

import ("fmt")

func main() {
	x := 1
	y := 2
	z := 3

	fmt.Println(x)
	fmt.Println(y)
	fmt.Println(z)
}

// 1
// 2
// 3

Since you can omit the type specification, you can improve the development efficiency by writing here.

Reference material

Learn the basic grammar of Go Learn golang from the basics: Control structure