Curriculum Collections Iteration with range exercise 5 · mcq
Iteration with range
Range over a MAP one-value-form: which one does Go emit, key or
value?
Compare with exercises 2 and 3 (slice): for x := range slice gives
the INDEX. Now MAPs: for x := range m gives the KEY. The same
range x syntax means different things by collection type.
TypeScript:
``ts
for (const k of Object.keys(cache)) {
console.log(k);
}
``
Pick the Go form that prints just the keys.
TypeScript reference
About this theme
for i, v := range collection is the workhorse. Over a slice you get (index, value). Over a map you get (key, value). Over a string you get (byteIndex, rune). Over a channel you get just the value, with no index. Use _ to discard either side.