Decision Making

STATEMENT	DESCRIPTION
if Statements	Block of statement executed only when specified test expression is true.
if else Statements	When we want to execute some block of code if a condition is true and another block of code if a condition is false, In such a case we use if….else statement.
nested If Statements	When there is an if statement inside another if statement then it is known as nested if else.
switch Statement	A switch statement evaluates an expression against multiple cases in order to identify the block of code to be executed.

Above statements are standard as in many other languages, such as C and Java.

If with short statement

In Go, the conditional expression can be preceded by a simple statement, which is executes before the conditional expression is evaluated, and if it is a declaration statement then the variable declared in the statement will only be available inside the if block and it’s else or else-if sections.

package main

import "fmt"

func main() {

	if x := 3; x%2 == 0 {
		fmt.Printf("%d is even\n", x)
	} else {
		fmt.Printf("%d is odd\n", x)
	}

}

3 is odd

Switch Statement (single cases)

package main

import "fmt"

func main() {
  var dayOfWeek = 5
	switch dayOfWeek {
	case 1:
		fmt.Println("Today is Monday.")
	case 2:
		fmt.Println("Today is Tuesday.")
	case 3:
		fmt.Println("Today is Wednesday.")
	case 4:
		fmt.Println("Today is Thursday.")
	case 5:
		fmt.Println("Today is Friday.")
	case 6:
		fmt.Println("Today is Saturday.")
	case 7:
		fmt.Println("Today is Sunday.")
	default:
		fmt.Println("Invalid weekday!")
	}
}

Today is Friday.

Switch Statement (multiple cases)

package main

import "fmt"

func main() {

	var dayOfWeek = 3
	switch dayOfWeek {
	case 1, 2, 3, 4, 5:
		fmt.Println("It's a weekday.")
	case 6, 7:
		fmt.Println("It's the weekend!")
	default:
		fmt.Println("Invalid day!")
	}

}

It's a weekday.

Switch Statement - fallthrough

All the following cases are executed after a match is found in the switch statement cases.

package main

import "fmt"

func main() {

	var x = 2
	switch x {
	case 1:
		fmt.Println("1")
		fallthrough
	case 2:
		fmt.Println("2")
		fallthrough
	case 3:
		fmt.Println("3")
	}

}

2
3

Switch Statement - Short Statement

Similar to short statement for if statement.

package main

import "fmt"

func main() {

	switch dayOfWeek := 5; dayOfWeek {
	case 1, 2, 3, 4, 5:
		fmt.Println("It's a weekday.")
	case 6, 7:
		fmt.Println("It's the weekend!")
	default:
		fmt.Println("Invalid day!")
	}

}

It's a weekday.

Switch Statement - No Expression

package main

import "fmt"

func main() {
	var marks = 40
	switch {    // same as `switch true`
	case marks > 60:
		fmt.Println("You got A!")
	case marks < 60 && marks >= 50:
		fmt.Println("You got B.")
	case marks < 50 && marks >= 35:
		fmt.Println("You got C :(")
	default:
		fmt.Println("Failed!")
	}
}

You got C :(