Go : Example 1

go-example1

package main

import (
	"fmt"
)

func main() {

	text := `The quick brown fox jumps over the lazy dog`
	vowels, spaces, constants := 0, 0, 0

	for _, char := range text {
		switch char {
		case 'a', 'e', 'i', 'o', 'u':
			vowels++
		case ' ':
			spaces++
		default:
			constants++
		}
	}

	fmt.Printf("Found %d vowels, %d spaces and %d constants", vowels, spaces, constants)
}




------
Loops
------


package main

import (
	"fmt"
)

func main() {

	stop := false
	i := 0
	for !stop {
		i++
		stop = i == 5
		fmt.Printf("Counter is at %d\n", i)
	}
	
	i = 0
	for i := 0; i < 5; i++ {
		fmt.Printf("Counter is at %d\n", i)
	}

	i = 0
	for i, j := 0, 1; i < 5; i, j = i+1, j*2 {
		fmt.Printf("Counter is at %d j = %d\n", i, j)
	}

}


----- 
function args and return values
-----

package main

import (
	"fmt"
)

func main() {
	starting()
	i := printer("hello", "world!")
	fmt.Printf("wrote out %d lines", i)
	msg, x := complete()
	
	fmt.Printf("%s %d", msg, x)
}


func starting() {
	printer("start")
}

func complete() (string, int) {
	msg := "complete\n";
	result := printer(msg)
	return msg, result
	
}

func printer(msgs ...string) (counter int) {
	counter = 0
	for i, msg := range msgs {
		counter++
		fmt.Printf(" %d: %s\n", i, msg)
	}
	return counter
}


------
array (slice)
------

package main

import (
	"fmt"
)

func main() {
	// this is a slice and is passed by reference
	words := []string{"the", "quick", "brown", "fox"}
	printer(words)
	printer(words[0:1])
	words[0] = "!!The!!"
	printer(words[0:1])
	printer(words[1:])
	
	newarray := append(words, "NEW")
	printer(words)
	printer(newarray)
}

func printer(words []string) {
	for _, word := range words {
		fmt.Printf("%s", word)
	}
	words[0] = "**The**"
}

----------
maps
----------

package main

import (
	"fmt"
)

func main() {
	// this is a slice and is passed by reference
	months := map[string]int{
		"jan": 31,
		"feb": 28,
	}

	printDaysInMonth(months, "jan")
	printDaysInMonth(months, "mar")
	months["mar"] = 31
	printDaysInMonth(months, "mar")
	printDaysInMonth(months, "Mar")
	printEachMonth(months)
}

func printDaysInMonth(months map[string]int, key string) {
	daysInMonth, ok := months[key]
	if !ok {
		fmt.Printf("key %s not found\n", key)
	} else {
		fmt.Printf("Days in month %s is %d\n", key, daysInMonth)
	}
}

func printEachMonth(months map[string]int) {
	for key, daysInMonth := range months {
		fmt.Printf("month %s has %d days\n", key, daysInMonth)
	}

}