'string','c2'=>'string','c3'=>'string','c4'=>'string'); $writer = new XLSXWriter(); $writer->writeSheetHeader('Sheet1', $header); for($i=0; $i<250000; $i++) { $s1 = substr($s, rand()%4000, rand()%5+5); $s2 = substr($s, rand()%8000, rand()%5+5); $s3 = substr($s, rand()%12000, rand()%5+5); $s4 = substr($s, rand()%16000, rand()%5+5); $writer->writeSheetRow('Sheet1', array($s1, $s2, $s3, $s4) ); } $writer->writeToFile('xlsx-strings-250k.xlsx'); echo '#'.floor((memory_get_peak_usage())/1024/1024)."MB"."\n";