Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Cell/Coordinate.php
public static function absoluteCoordinate($pCoordinateString)
    {
        if (self::coordinateIsRange($pCoordinateString)) {
            throw new Exception('Cell coordinate string can not be a range of cells');
        }

        // Split out any worksheet name from the coordinate
        $worksheet = '';
        $cellAddress = explode('!', $pCoordinateString);
        if (count($cellAddress) > 1) {
            list($worksheet, $pCoordinateString) = $cellAddress;
        }
        if ($worksheet > '') {
            $worksheet .= '!';
        }

        // Create absolute coordinate
        list($column, $row) = self::coordinateFromString($pCoordinateString);
        $column = ltrim($column, '$');
        $row = ltrim($row, '$');

        return $worksheet . '$' . $column . '$' . $row;
    }
public static function absoluteCoordinate($pCoordinateString)
    {
        if (self::coordinateIsRange($pCoordinateString)) {
            throw new Exception('Cell coordinate string can not be a range of cells');
        }

        // Split out any worksheet name from the coordinate
        $worksheet = '';
        $cellAddress = explode('!', $pCoordinateString);
        if (count($cellAddress) > 1) {
            list($worksheet, $pCoordinateString) = $cellAddress;
        }
        if ($worksheet > '') {
            $worksheet .= '!';
        }

        // Create absolute coordinate
        list($column, $row) = self::coordinateFromString($pCoordinateString);
        $column = ltrim($column, '$');
        $row = ltrim($row, '$');

        return $worksheet . '$' . $column . '$' . $row;
    }
Make string coordinate absolute.

@param string $pCoordinateString e.g. 'A1'

@throws Exception

@return string Absolute coordinate        e.g. '$A$1'