Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Collection/Cells.php
public function getHighestRow($column = null)
    {
        if ($column == null) {
            $colRow = $this->getHighestRowAndColumn();

            return $colRow['row'];
        }

        $rowList = [0];
        foreach ($this->getCoordinates() as $coord) {
            sscanf($coord, '%[A-Z]%d', $c, $r);
            if ($c != $column) {
                continue;
            }
            $rowList[] = $r;
        }

        return max($rowList);
    }
public function getHighestRow($column = null)
    {
        if ($column == null) {
            $colRow = $this->getHighestRowAndColumn();

            return $colRow['row'];
        }

        $rowList = [0];
        foreach ($this->getCoordinates() as $coord) {
            sscanf($coord, '%[A-Z]%d', $c, $r);
            if ($c != $column) {
                continue;
            }
            $rowList[] = $r;
        }

        return max($rowList);
    }
Get highest worksheet row.

@param string $column Return the highest row for the specified column,
or the highest row of any column if no column letter is passed

@return int Highest row number