src/YearMonthRange.php
public function count() : int
    {
        return 12 * ($this->end->getYear() - $this->start->getYear())
            + ($this->end->getMonth() - $this->start->getMonth())
            + 1;
    }
public function count() : int
    {
        return 12 * ($this->end->getYear() - $this->start->getYear())
            + ($this->end->getMonth() - $this->start->getMonth())
            + 1;
    }
public function count ( ) : int { return 12 * ( $ this -> end -> getYear ( ) - $ this -> start -> getYear ( ) ) + ( $ this -> end -> getMonth ( ) - $ this -> start -> getMonth ( ) ) + 1 ; }
Returns the number of year-months in this range.

@return int The number of year-months, >= 1.
Returns the number of year - months in this range .