You can compare two index values by using the compare method.
$text->compare(index1, op, index2);
You pass the first index, the test operation to perform, and the second index. The values for op are: "<", "<=", "==", ">=", and "!=". The function returns 1 if the test is true and 0 if it isn't. The following call returns 1 because the index "1.0" is less than "end":
$status = $text->compare("1.0", "<=", "end");