Go loop

This program covers every variation of the for loop in Go, which is the only loop construct in the language. It demonstrates basic incrementing loops, iterating with two variables, omitting the initializer, while-style loops, infinite loops with break, the continue keyword for skipping iterations, labeled loops for breaking out of nested loops, and range-based iteration over slices, maps, and strings.

package main

import (
	"fmt"
	// "strconv"
	// "math"
	// "reflect"
	// "math"
)

func basicLoop()  {
	for i := 0; i < 5; i++ {
		fmt.Printf("Number: %v\n", i)
	}
}


func everyOther()  {
	for i := 0; i < 5; i = i + 2 {
		fmt.Printf("Number: %v\n", i)
	}
}

func loopOverTwoVariables()  {
	for i, j := 0, 0; i < 5; i, j = i + 1, j + 3 {
		fmt.Printf("i: %v, j: %v\n", i, j)
	}
}

func play()  {
	for i:= 0; i < 5; i++ {
		fmt.Printf("Number: %v\n", i)
		if i%2 == 0 {
			i /= 2
		} else {
			i = 2*i + 1
		}
	}
}


func initializerAtSomeOtherPlace()  {
	i := 0
	for ; i < 5; i++ {
		fmt.Printf("Number: %v\n", i)
	}
}

func pythonLike()  {
	i := 0
	// for i < 5 {   <- works just fine withour semicolons
	for ; i < 5 ; {
		fmt.Printf("Number: %v\n", i)
		i++
	}
}

func infiniteForLoop()  {
	i := 0
	for {
		fmt.Printf("Number: %v\n", i)
		i++
	}
}


func infiniteForLoopWithBreak()  {
	i := 0
	for {
		fmt.Printf("Number: %v\n", i)
		i++
		if i == 5 {
			fmt.Printf("Breaking from Infinite Loop! number: %v\n", i)
			break
		}
	}
}


func forLoopWithContinueKeyWork()  {
	for i := 0; i < 10; i ++ {
		if i%2 == 0 {
			// the keyword "continue" is a special keyword
			// and if this condition above is true that we
			// stop here and don't go and print anything !!!
			// we sort of continuing back to main loop
			continue
		}
		fmt.Printf("Number: %v\n", i)
	}
}

func nestedForLoop()  {
	for i := 1; i <= 3; i++ {
		for j := 1; j <=4; j++ {
			fmt.Printf("Multiply %v(i) * %v(j) = %v\n", i, j, i*j)
		}
	}
}


func breakOutOfNestedForLoop()  {
// This "label" below "tells to" the "break" keyword
// which loop to exit!!! Please notice that if this label not used
// only inner most loop would be exited
Labelloop:
	for i := 1; i <= 3; i++ {
		for j := 1; j <=4; j++ {
			fmt.Printf("Multiply %v(i) * %v(j) = %v\n", i, j, i*j)
			if i * j >= 3 {
				fmt.Printf("Breaking out of nested for loop because of condition based on label!!!\n")
				break Labelloop
			}
		}
	}
}


func collectionForLoop()  {
	s := []int{1, 2, 3}
	fmt.Printf("Element: %v\n", s)
	fmt.Println("")
	for k, v := range s {
		fmt.Printf("Element: %v(k): %v(v)\n", k, v)
	}
	fmt.Println("")
	// maps
	statePopulation := make(map[string]int)
    statePopulation = map[string]int{
        "California": 2341232,
        "Texas": 3341232,
        "Florida": 4341232,
        "New York": 5341232,
        "Illinois": 6341232,
        "Ohio": 7341232,
	}

	fmt.Println("")
	for k,v := range statePopulation {
		fmt.Printf("Element: %v(k): %v(v)\n", k, v)
	}

	fmt.Println()
	//  if we only care for "keys"
	for k := range statePopulation {
		fmt.Printf("Element: %v(k)\n", k)
	}

	fmt.Println("")
	//  if we only care for "values"
	for _, v := range statePopulation {
		fmt.Printf("Element: %v(v)\n", v)
	}
	fmt.Println("")
	// strings
	st := "hello Go!"
	for k, v := range st {
		fmt.Printf("Element: %v(k): %v(v), %v(v) \n", k, v, string(v))
	}


}

func main() {
	// basicLoop()
	// everyOther()
	// loopOverTwoVariables()
	// play()
	// initializerAtSomeOtherPlace()
	// pythonLike()
	// infiniteForLoop()
	// infiniteForLoopWithBreak()
	// forLoopWithContinueKeyWork()
	// nestedForLoop()
	// breakOutOfNestedForLoop()
	collectionForLoop()
}