How to center the text in PHPExcel merged cell

How to center text “test”?

This is my code:

<?php
    /** Error reporting */
    error_reporting(E_ALL);
    ini_set('display_errors', TRUE);
    ini_set('display_startup_errors', TRUE);
    date_default_timezone_set('Europe/London');

    /** Include PHPExcel */
    require_once '../Classes/PHPExcel.php';

    $objPHPExcel = new PHPExcel();
    $sheet = $objPHPExcel->getActiveSheet();
    $sheet->setCellValueByColumnAndRow(0, 1, "test");
    $sheet->mergeCells('A1:B1');
    $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
    $objWriter->save("test.xlsx");

Output Excel document:

Answer

if you want to align only this cells, you can do something like this:

    $style = array(
        'alignment' => array(
            'horizontal' => PHPExcel_Style_Alignment::HORIZONTAL_CENTER,
        )
    );

    $sheet->getStyle("A1:B1")->applyFromArray($style);

But, if you want to apply this style to all cells, try this:

    $style = array(
        'alignment' => array(
            'horizontal' => PHPExcel_Style_Alignment::HORIZONTAL_CENTER,
        )
    );

    $sheet->getDefaultStyle()->applyFromArray($style);