Im using setcellValue to populate my excel file, but the moment it reaches A99, it throws this error
Fatal error: Uncaught exception 'Exception' with message 'Column string index can not be longer than 3 characters.'
is it a limitation that phpexcel has, or am i making a mistake by populating my sheet in this format
$objPHPExcel->getActiveSheet()->setcellValue($alpha[$alpha_count] . $spreadsheet_count, $row['comment']);
Maybe you could try with setCellValueByColumnAndRow() :
setCellValueByColumnAndRow($alpha_count, $spreadsheet_count, $row['comment']);
No it doesn't mean that that PHPExcel supports only 100 rows, PHPExcel supports up to 1,048,576 rows and up to 16,384 columns (same as the OfficeOpenXML format for xlsx files)... dependent on memory.
Your column string index that the error message refers to is the column reference (the A of A100).
Double check exactly what the value of $alpha[$alpha_count] is, I suspect it isn't what you think.