Golang conditionals

If Not

if !(1 == 0) {
    fmt.Println("hi")
}

If Statements

if 1 > 0 {
    // ...
} else if 2 > 0 {
    // ...
} else {
    // ...
}

Similar to for loops, go's if statements can use an initializer.

if err := file.Chmod(0664); err != nil {
    log.Print(err)
}

// common in hash tests
if _, ok := myMap["someKey"]; ok {
    // eval if key present
}

Short Circuiting

// the final 'false' is never evaluated, because the second is true
if false || true || false { ... }

// same deal with elses
if false {
    // ...
} else if true {
    // ...
} else if false {  // <-- expression never evaluated
    // ...
}

Switch Statements

Control flow

break        // exit switch statement early
fallthrough  // continue evaluating switch, when true

Regular switch statements that test specific variable

switch var {
case 'a', 'b', 'c':
    fmt.Println("is a, b, or c")
case 'd', 'e', 'f':
    fmt.Println("is d, e, or f")
default:
    fmt.Println("default behaviour")
}

Switch statements can also test different variables

switch {
case '0' <= number:
    fmt.Println("is zero")
case 'a' <= letter:
    fmt.Println("is a")
}

You may also force evaluate sections even if one case is matched with falthrough.

require "strings"

var  arch      string
var  wordsize  string

cpuarch := "x86-64"

switch {
case strings.HasPrefix(cpuarch, "x86"):
    arch = "x86"
    fallthrough   // <-- continue to next case statement, even when evaluates to true
case strings.Split(cpuarch, "-")[1] == "64":
    wordsize = 64
}

You can also swith on variable type.

wordsize := 64

switch wordsize.(type) {
    int:
        // ...
    string:
        // ...
}