Code-Memo

For loop

Go has only one looping keyword: for. The same keyword covers C-style for, while, and for-ever.

Classic three-part for

for i := 0; i < 10; i++ {
	println(i)
}

Condition-only (while-style)

for n < 100 {
	n *= 2
}

Infinite loop

for {
	if shouldStop() {
		break
	}
}

Range over slice, array, string, map, channel

for i, v := range slice {
	_, _ = i, v
}

for k, v := range m {
	_, _ = k, v
}

for i, r := range "Hi" { // i byte offset, r rune
	_, _ = i, r
}

If you only need the value, use _ for the index/key.

Labels and break/continue

A labeled break exits the outer loop.

Outer:
	for i := 0; i < 3; i++ {
		for j := 0; j < 3; j++ {
			if i*j > 2 {
				break Outer
			}
		}
	}

Common pitfalls

• Range captures index and value; the value variable is reused each iteration — do not take its address expecting distinct variables per iteration without a local copy inside the loop body.
• Modifying the map while ranging over it is defined for deletion of the current key; other patterns need care.