MultipleIterator::valid
  (PHP 5 >= 5.3.0, PHP 7, PHP 8)
MultipleIterator::valid — Checks the validity of sub iterators
  
 
  说明
  
   public MultipleIterator::valid(): 
bool 
  
  
  
 
 
  返回值
  
   Returns true if one or all sub iterators are valid depending on flags,
   otherwise false