(PHP 5, PHP 7, PHP 8)
CachingIterator::key โ Return the key for the current element
ๆฌๅฝๆฐ่ฟๆช็ผๅๆๆกฃ๏ผไป ๆๅๆฐๅ่กจใ
This method may return a key for the current element.
ๆญคๅฝๆฐๆฒกๆๅๆฐใ
