(PHP 5 >= 5.3.0, PHP 7)
RecursiveTreeIterator::valid — Check validity
Check whether the current position is valid.
锟斤拷锟斤拷锟斤拷锟斤拷未锟斤拷写锟侥碉拷锟斤拷锟斤拷锟叫诧拷锟斤拷锟叫憋拷
锟剿猴拷锟斤拷没锟叫诧拷锟斤拷锟斤拷
TRUE if the current position is valid, otherwise FALSE
TRUE
FALSE