how to convert xls file to csv file in php code?
['function excel_csv_to_csv($in_file, $out_file) {', 'if( !$ ... ', '$fw = fopen($out_file, "w");', 'while( ($data = fgetcsv($fr, 1000, ",")) !== FALSE ) {', 'foreach( array_keys($data) as $key )', '$data[$key] = \'"\' . ... ', '$line = implode(",", $data) . " ... ', 'fwrite($fw, $line);']