Basic example to read tab delimited file
$fp = fopen('mydata.csv', 'r');
while ( !feof($fp) )
{
$line = fgets($fp, 2048);
$someCondition = someConditionToDetermineTabOrComma();
$delimiter = $someCondition ? "," : "\t";
$data = str_getcsv($line, $delimiter);
doSomethingWithData($data);
}
fclose($fp);