The One Loop: for

Computers are champions at doing the same thing many times without getting bored. Where other languages have while loops, do loops, and more, Go has exactly one keyword for repetition: for. It just wears a few different outfits.

Outfit one: the counting loop

for i := 0; i < 5; i++ {
    fmt.Println("Lap number", i)
}

This prints lap numbers 0 through 4. The header has three parts separated by semicolons:

1. Setup: i := 0 runs once, creating the counter.
2. Condition: i < 5 is checked before every lap. While it is true, the loop keeps going.
3. Step: i++ runs after every lap and means add 1 to i.

Counting from 0 feels odd at first, but it matches how lists are numbered in Go, so it quickly becomes natural.

Outfit two: the while-style loop

Drop the setup and step, keep only the condition, and for behaves like the while loop from other languages:

energy := 10

for energy > 0 {
    fmt.Println("Still running! Energy:", energy)
    energy = energy - 3
}

The loop keeps going as long as the condition stays true. Something inside the loop must move toward making it false, or the loop will never end.

Outfit three: the forever loop

for {
    fmt.Println("This would print forever...")
    break
}

A bare for loops forever. That sounds like a bug, but servers use exactly this shape: wait for a request, handle it, repeat forever. The break keyword jumps out of the loop immediately.

Two loop controls

• break leaves the loop right now.
• continue skips the rest of this lap and starts the next one.

for i := 1; i <= 10; i++ {
    if i % 2 == 0 {
        continue
    }
    fmt.Println(i)
}

This prints only the odd numbers from 1 to 9: whenever i is even, continue skips the print.