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Control Flow

If Statements

package main

import (
    "fmt"
)

func main() {
    if true {
        fmt.Println("This test is true")
    }
}

package main

import (
    "fmt"
)

func main() {
    pokemon := map[string]string {
        "Charmander": "Kanto",
        "torchic":  "Hoenn",
        "Chimchar": "Sinnoh",

    }
    if pop, ok := pokemon["torchic"]; ok {
        fmt.Printf(pop)
    }
}

Operators

package main

import (
    "fmt"
)

func main() {
    number := 50
    guess := 24

    if guess < 1 || guess > 100 {
        fmt.Println("The guess must between 1 and 100")
    }

    if guess >= 1 && guess <= 100 {
        if guess < number {
            fmt.Println("To Low")
        }
        if guess > number {
            fmt.Println("To High")
        }
        if guess == number {
            fmt.Println("You got it!")
        }

        fmt.Println(number <= guess, number >= guess, number != guess)
    }
    fmt.Println(!true)
}
- go exits logical tests early (short circuiting) - escape or test on first true condition - escape and test on first false condition

If-else and if-else if statements

package main

import (
    "fmt"
)

func main() {

    // else statement
    number := 50
    guess := 24

    if guess < 1 || guess > 100 {
        fmt.Println("The guess must between 1 and 100")
    } else {
        if guess < number {
            fmt.Println("To Low")
        }
        if guess > number {
            fmt.Println("To High")
        }
        if guess == number {
            fmt.Println("You got it!")
        }

        fmt.Println(number <= guess, number >= guess, number != guess)
    }
}

package main

import (
    "fmt"
)

func main() {
    number := 50
    guess := 24

    if guess < 1 {
        fmt.Println("The guess must be greater 1")
    } else if guess > 100 {
        fmt.Println("The guess must be less than 100")
    } else {
        if guess < number {
            fmt.Println("To Low")
        }
        if guess > number {
            fmt.Println("To High")
        }
        if guess == number {
            fmt.Println("You got it!")
        }

        fmt.Println(number <= guess, number >= guess, number != guess)
    }
}
- go exits on the first matching if-else if case

Switch Statements

  • special purpose if statements
  • can't have overlapping cases

Simple Cases

package main

import (
    "fmt"
)

func main() {
    switch 1 {
    case 1:
        fmt.Println("one")
    case 2:
        fmt.Println("two")
    default:
        fmt.Println("not one or two")
    }  
}

Cases With Multiple Tests

package main

import (
    "fmt"
)

func main() {
    switch 1 {
    case 1, 3, 5:
        fmt.Println("one. three, or five")
    case 2, 4, 6:
        fmt.Println("two, four, or six")
    default:
        fmt.Println("not one through 6")
    }  
}

package main

import (
    "fmt"
)

func main() {
    // initialize switch value
    switch i:= 2+3;i {
    case 1, 3, 5:
        fmt.Println("one. three, or five")
    case 2, 4, 6:
        fmt.Println("two, four, or six")
    default:
        fmt.Println("not one through 6")
    }  
}

package main

import (
    "fmt"
)

func main() {
    // un-tgged switch statements
    i:= 10
    switch {
    case i <= 10:
        fmt.Println("less than or equal to ten")
    case i <= 20:
        fmt.Println("less than or equal to ten")
    default:
        fmt.Println("greater than 20")
    }  
}

Falling through

  • make go to next case 
    package main

import (
    "fmt"
)

func main() {
    // fallthrough key word
    i:= 10
    switch {
    case i <= 10:
        fmt.Println("less than or equal to ten")
        fallthrough
    case i <= 20:
        fmt.Println("less than or equal to ten")
    default:
        fmt.Println("greater than 20")
    }  
}

Type Switches

package main

import (
    "fmt"
)

func main() {
    // interface can take any type assignment
    var i interface{} = 1

    // get i  type
    switch i.(type) {
    case int:
        fmt.Println("i is an int")
    case float32:
        fmt.Println("i is a float32")
    case string:
        fmt.Println("i is  a string")
    default:
        fmt.Println("i is another type0")
    }  
}

Break

  • exit a case statement early 
    package main

import (
    "fmt"
)

func main() {
    // interface can take any type assignment
    var i interface{} = 1

    // get i  type
    switch i.(type) {
    case int:
        fmt.Println("i is an int")
        break
        fmt.Println("this wont be printed")
    case float32:
        fmt.Println("i is a float32")
    case string:
        fmt.Println("i is  a string")
    default:
        fmt.Println("i is another type0")
    }  
}