'string','c2'=>'integer','c3'=>'integer','c4'=>'integer','c5'=>'integer'); $writer = new XLSXWriter(); $writer->writeSheetHeader('Sheet1', $header, ['freeze_rows'=>1, 'freeze_columns'=>1] ); for($i=0; $i<250; $i++) { $writer->writeSheetRow('Sheet1', array( str_shuffle($chars), rand()%10000, rand()%10000, rand()%10000, rand()%10000 )); } $writer->writeToFile('xlsx-freeze-rows-columns.xlsx'); echo '#'.floor((memory_get_peak_usage())/1024/1024)."MB"."\n";