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Switch Statements

2:25 with Jay McGavren

To choose between several options with "if" / "else" statements, you'd have to nest them several deep, which is hard to read. So like most programming languages, Go offers a "switch" statement. You specify the expression you want to switch on, "case" statements with possible values for that expression, and one or more lines of code that should run in each case.

  • To choose between several options with if / else statements, you'd have to nest them several deep, which is hard to read
  • So like most programming languages, Go offers a switch statement.
  • You specify the expression you want to switch on, case statements with possible values for that expression, and one or more lines of code that should run in each case.
  • You can add a default case at the end, that will run if none of the other cases match.
package main

import (
    "fmt"
)

func main() {
    fmt.Print("You win: ")
    doorNumber := 2
    switch doorNumber {
    case 1:
        fmt.Println("a new car!") // not printed
    case 2:
        fmt.Println("a llama!") // printed
    default:
        fmt.Println("a goat!") // not printed
    }
}
  • 0:00

    To choose between several different options, using if and

  • 0:03

    else states, you'd have to nest some several deep, which can be hard to read.

  • 0:07

    So like most programming languages, Go offers a switch statement.

  • 0:11

    You specify the expression you wanna switch on, case statements with

  • 0:14

    possible values for that expression, and then code that should run for each case.

  • 0:20

    You can also add the default case at the end,

  • 0:22

    that will run if none of the other cases match.

  • 0:25

    So up here, we've initialized the doorNumber variable with the value 2,

  • 0:30

    the integer 2.

  • 0:32

    And we're going to switch on the value that's in doorNumber.

  • 0:35

    So we've got case statements here, for possible values of doorNumber.

  • 0:38

    If doorNumber was set to 1, we would print the string, a new car!

  • 0:44

    But up here, it's actually set to 2, so

  • 0:47

    it's going to match this case here, case number 2.

  • 0:51

    And it means that his code here will run, it will print the string, a llama!

  • 0:57

    So if we try running this down here, we'll see, You win a llama!

  • 1:01

    Let's try going up here into the code and setting it to 1, so

  • 1:04

    that we can look at the other case.

  • 1:07

    Try running this again.

  • 1:08

    This time, you can see we won a new car.

  • 1:10

    And if we set it to some completely different value,

  • 1:14

    let's say we pick door number 99.

  • 1:16

    In that case none of the cases here will match, and

  • 1:20

    therefore the default case will run instead.

  • 1:24

    And it will print, You win a goat!

  • 1:27

    Let's change this back to doorNumber 1, up here.

  • 1:31

    In some languages, the case after the selected case will also run,

  • 1:34

    unless you insert a break statement at the end of the case.

  • 1:37

    In Go, only the selected case runs by default.

  • 1:40

    So, if we select doorNumber 1, only doorNumber 1 runs.

  • 1:43

    But you can run the next case as well,

  • 1:46

    if you explicitly include the fallthrough keyword.

  • 1:51

    So lets type fallthrough here, and try re-running it.

  • 1:55

    And now, we win both a new car and a llama.

  • 1:58

    That ends our tour of control structures in Go.

  • 2:01

    Go's a very simple language, so

  • 2:03

    you've actually learned a substantial part of its syntax already.

  • 2:08

    The next stage is going to be a bit longer than this one.

  • 2:10

    We're going to look at the different ways Go can store data, and

  • 2:13

    there are a lot of them.

  • 2:15

    We'll learn about slices, maps, structs and more.

  • 2:18

    Learning them will take a bit of work, but

  • 2:19

    when you're done, you'll have a variety of ways to simplify your programs.

  • 2:23

    See in the next stage.

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