Control Flow: switch (Multi-Way Branching & Type Switch) - Go Tutorial for Beginners #7

Control Flow: switch (Multi-Way Branching & Type Switch) in Go

Switch statements in Go provide a clean and concise way to perform multi-way branching without needing explicit breaks. This tutorial covers basic switch usage, handling multiple values in cases, expressionless switches that behave like if-else chains, the fallthrough keyword, and type switches for interface types.

Code

package main

import (
  "fmt"
)

func main() {
  // Basic switch statement
  day := "Tuesday"
  switch day {
  case "Monday":
    fmt.Println("Start of the work week")
  case "Tuesday", "Wednesday", "Thursday":
    fmt.Println("Midweek days")
  case "Friday":
    fmt.Println("Almost weekend")
  default:
    fmt.Println("Weekend!")
  }

  // Expressionless switch (like if-else)
  num := 7
  switch {
  case num < 0:
    fmt.Println("Negative number")
  case num == 0:
    fmt.Println("Zero")
  case num > 0:
    fmt.Println("Positive number")
  }

  // Using fallthrough to continue to next case
  grade := 'B'
  switch grade {
  case 'A':
    fmt.Println("Excellent")
  case 'B':
    fmt.Println("Good")
    fallthrough // continue to next case
  case 'C':
    fmt.Println("Average")
  default:
    fmt.Println("Needs Improvement")
  }

  // Type switch to determine the type of interface{}
  var i interface{} = 42
  switch v := i.(type) {
  case int:
    fmt.Printf("Integer: %d\n", v)
  case string:
    fmt.Printf("String: %s\n", v)
  default:
    fmt.Println("Unknown type")
  }
}

Key Points

• Go's switch statements do not require explicit breaks; cases automatically break after execution.
• Multiple values can be handled in a single case by separating them with commas.
• Expressionless switches allow evaluating boolean expressions similar to if-else chains.
• The fallthrough keyword forces execution to continue to the next case regardless of matching.
• Type switches let you branch logic based on the dynamic type of an interface value.