PhpSpreadsheet/samples/Basic/16_Csv.php

<?php

use PhpOffice\PhpSpreadsheet\IOFactory;

require __DIR__ . '/../Header.php';
$spreadsheet = require __DIR__ . '/../templates/sampleSpreadsheet.php';

$helper->log('Write to CSV format');
$writer = IOFactory::createWriter($spreadsheet, 'Csv')->setDelimiter(',')
    ->setEnclosure('"')
    ->setSheetIndex(0);

$callStartTime = microtime(true);
$filename = $helper->getTemporaryFilename('csv');
$writer->save($filename);
$helper->logWrite($writer, $filename, $callStartTime);

$helper->log('Read from CSV format');

$reader = IOFactory::createReader('Csv')->setDelimiter(',')
    ->setEnclosure('"')
    ->setSheetIndex(0);

$callStartTime = microtime(true);
$spreadsheetFromCSV = $reader->load($filename);
$helper->logRead('Csv', $filename, $callStartTime);

// Write Xlsx
$helper->write($spreadsheetFromCSV, __FILE__, ['Xlsx']);

// Write CSV
$filenameCSV = $helper->getFilename(__FILE__, 'csv');
$writerCSV = IOFactory::createWriter($spreadsheetFromCSV, 'Csv');
$writerCSV->setExcelCompatibility(true);

$callStartTime = microtime(true);
$writerCSV->save($filenameCSV);
$helper->logWrite($writerCSV, $filenameCSV, $callStartTime);