Summary - Control flow
- Go course
- Beginner
- Lesson 40/90
- 4 min
Combine if, for and switch to write a score calculator.
Control flow summary
Decisions: if / else if / else (the condition must be a bool and can take a short statement) and switch (comma cases, expressionless switch, rarely fallthrough). Loops: the single keyword for — counter, condition, infinite and range. Flow control: break, continue, labels.
for i := range 15 {
switch {
case i%15 == 0:
fmt.Println("FizzBuzz")
case i%3 == 0:
fmt.Println("Fizz")
}
}Early return
Go code prefers "early return" over nested if-else: error or special cases are handled at the top and the function returns, keeping the main flow unindented.
func indirim(tutar float64, uye bool) float64 {
if tutar <= 0 {
return 0
}
if !uye {
return tutar
}
return tutar * 0.9
}Practice FizzBuzz
For the numbers 1 to 15: print FizzBuzz if divisible by 15, Fizz if divisible by 3, Buzz if divisible by 5, otherwise the number itself. Print them all on one line separated by spaces (with fmt.Print, then fmt.Println() at the end).
Starter code
package main
import "fmt"
func main() {
// buraya yaz
}Sample solution
package main
import "fmt"
func main() {
for i := 1; i <= 15; i++ {
switch {
case i%15 == 0:
fmt.Print("FizzBuzz ")
case i%3 == 0:
fmt.Print("Fizz ")
case i%5 == 0:
fmt.Print("Buzz ")
default:
fmt.Print(i, " ")
}
}
fmt.Println()
}Expected output
1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 In FizzBuzz, why must the <code>i%15 == 0</code> check come first?
- Multiples of 15 are also divisible by 3; if 3 comes first it prints "Fizz" Correct answer
- It's faster
- Go requires it
- The order doesn't matter
Explanation: In an expressionless switch the first true case runs; the most specific condition is written at the top.
2 range over integers
for i := ____ 3 {
fmt.Println(i) // 0 1 2
}for i := range 3 {
fmt.Println(i) // 0 1 2
}Explanation: Since Go 1.22, range over an integer counts from 0 to n-1.
3 Group summary
| Term | Meaning |
|---|---|
if-else |
Decision |
switch |
Multi-way decision |
for |
All loops |
break / continue |
Loop control |