Preview Ruby 4.1 is a preview. It can change before the final release. Switch to Ruby 4.0 →
instance method
Hash#each_key
() -> ::Enumerator[K, self]
() { (K key) -> void } -> self
each_key {|key| ... } → self
each_key → new_enumerator
hash.c
View on GitHub ↗
static VALUE
rb_hash_each_key(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_foreach(hash, each_key_i, 0);
return hash;
}
With a block given, calls the block with each key; returns self:
Example
h = {foo: 0, bar: 1, baz: 2} h.each_key {|key| puts key } # => {foo: 0, bar: 1, baz: 2}
Output:
Example
foo bar baz
With no block given, returns a new Enumerator.
Related: see Methods for Iterating.