Go — If Else

Basic if

package main

import "fmt"

func main() {
    temperature := 28

    if temperature > 25 {
        fmt.Println("It's warm outside!")
    }
}

if-else

hour := 14

if hour < 12 {
    fmt.Println("Good morning!")
} else {
    fmt.Println("Good afternoon!")
}

if-else if-else

score := 85

if score >= 90 {
    fmt.Println("Grade: A")
} else if score >= 80 {
    fmt.Println("Grade: B")
} else if score >= 70 {
    fmt.Println("Grade: C")
} else {
    fmt.Println("Grade: F")
}

if with init statement

if num := 42; num > 0 {
    fmt.Println("Positive:", num)
}

switch statement

day := "Monday"

switch day {
case "Monday":
    fmt.Println("Start of week")
case "Friday":
    fmt.Println("Almost weekend")
case "Saturday", "Sunday":
    fmt.Println("Weekend!")
default:
    fmt.Println("Midweek")
}

switch without expression

switch {
case score >= 90:
    grade = "A"
case score >= 80:
    grade = "B"
case score >= 70:
    grade = "C"
default:
    grade = "F"
}

type switch

var i interface{} = "hello"

switch v := i.(type) {
case int:
    fmt.Printf("Integer: %d\n", v)
case string:
    fmt.Printf("String: %s\n", v)
case bool:
    fmt.Printf("Boolean: %t\n", v)
default:
    fmt.Printf("Unknown type: %T\n", v)
}

fallthrough

n := 2

switch n {
case 1:
    fmt.Println("One")
    fallthrough // Falls through to next case
case 2:
    fmt.Println("Two")
    fallthrough
case 3:
    fmt.Println("Three")
}
// Output: Two Three

Combining conditions

age := 25
income := 50000

if age >= 18 && income >= 30000 {
    fmt.Println("Qualifies for premium card")
}

if age < 12 || age > 65 {
    fmt.Println("Discounted ticket")
}

Best practices

• Use if with init statement for short-lived variables
• Prefer switch over long if-else if chains
• Don't use fallthrough unless necessary
• Go doesn't have a ternary operator — use if-else

Mini Practice

Write Go code that:

1. Uses if with init statement to check a value
2. Uses switch to match a day of the week
3. Uses type switch on an interface{}
4. Combines conditions with && and ||

Up Next

In the next lesson, you'll learn about Switch — Go's switch statement in depth.