Creating spreadsheet with PHPExcel - phpexcel

Question

I am trying to write to a .xls file with PHP. I have tried many examples of code picked up from various sites, but get the same error each time:
Fatal error: Cannot redeclare class PHPExcel in .... line 44
This suggests that I have included PHPExcel more than once, but this is not the case. Can anyone give me a pointed to what I am doing wrong?
Thanks in advance.
Here is my code:
<?php
// include PHPExcel
require_once 'PHPExcel.php';
error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);
// create new PHPExcel object
$objPHPExcel = new PHPExcel;
// set default font
$objPHPExcel->getDefaultStyle()->getFont()->setName('Calibri');
// set default font size
$objPHPExcel->getDefaultStyle()->getFont()->setSize(8);
// create the writer
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, "Excel2007");
/** * Define currency and number format. */
// currency format, € with < 0 being in red color
$currencyFormat = '#,#0.## \€;[Red]-#,#0.## \€';
// number format, with thousands separator and two decimal points.
$numberFormat = '#,#0.##;[Red]-#,#0.##';
// writer already created the first sheet for us, let's get it
$objSheet = $objPHPExcel->getActiveSheet();
// rename the sheet
$objSheet->setTitle('My sales report');
// let's bold and size the header font and write the header
// as you can see, we can specify a range of cells, like here: cells from A1 to A4
$objSheet->getStyle('A1:D1')->getFont()->setBold(true)->setSize(12);
// write header
$objSheet->getCell('A1')->setValue('Product');
$objSheet->getCell('B1')->setValue('Quanity');
$objSheet->getCell('C1')->setValue('Price');
$objSheet->getCell('D1')->setValue('Total Price');
// we could get this data from database, but for simplicty, let's just write it
$objSheet->getCell('A2')->setValue('Motherboard');
$objSheet->getCell('B2')->setValue(10);
$objSheet->getCell('C2')->setValue(5);
$objSheet->getCell('D2')->setValue('=B2*C2');
$objSheet->getCell('A3')->setValue('Processor');
$objSheet->getCell('B3')->setValue(6);
$objSheet->getCell('C3')->setValue(3);
$objSheet->getCell('D3')->setValue('=B3*C3');
$objSheet->getCell('A4')->setValue('Memory');
$objSheet->getCell('B4')->setValue(10);
$objSheet->getCell('C4')->setValue(2.5);
$objSheet->getCell('D4')->setValue('=B4*C4');
$objSheet->getCell('A5')->setValue('TOTAL');
$objSheet->getCell('B5')->setValue('=SUM(B2:B4)');
$objSheet->getCell('C5')->setValue('-');
$objSheet->getCell('D5')->setValue('=SUM(D2:D4)');
// bold and resize the font of the last row
$objSheet->getStyle('A5:D5')->getFont()->setBold(true)->setSize(12);
// set number and currency format to columns
$objSheet->getStyle('B2:B5')->getNumberFormat()->setFormatCode($numberFormat);
$objSheet->getStyle('C2:D5')->getNumberFormat()->setFormatCode($currencyFormat);
// create some borders
// first, create the whole grid around the table
$objSheet->getStyle('A1:D5')->getBorders()->
getAllBorders()->setBorderStyle(PHPExcel_Style_Border::BORDER_THIN);
// create medium border around the table
$objSheet->getStyle('A1:D5')->getBorders()->
getOutline()->setBorderStyle(PHPExcel_Style_Border::BORDER_MEDIUM);
// create a double border above total line
$objSheet->getStyle('A5:D5')->getBorders()->
getTop()->setBorderStyle(PHPExcel_Style_Border::BORDER_DOUBLE);
// create a medium border on the header line
$objSheet->getStyle('A1:D1')->getBorders()->
getBottom()->setBorderStyle(PHPExcel_Style_Border::BORDER_MEDIUM);
// autosize the columns
$objSheet->getColumnDimension('A')->setAutoSize(true);
$objSheet->getColumnDimension('B')->setAutoSize(true);
$objSheet->getColumnDimension('C')->setAutoSize(true);
$objSheet->getColumnDimension('D')->setAutoSize(true);
// write the file
$objWriter->save('test.xlsx');
?>