Hi Burak,
Instead of removing leading zeros from internal table, why dont you append zeros to select options high and low values or declare the select options of the type containing leading zeros.
Use FM CONVERSION_EXIT_ALPHA_INPUT to pad zeros to the number at the left .
E.g
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
EXPORTING
input = S_VARIABLE-LOW
IMPORTING
OUTPUT = S_VARIABLE-LOW.
Similarly, do for high value of Select options.
After padding zeros, you can compare these values with internal table.
Or else if want to change the internal table values, use the function module CONVERSION_EXIT_ALPHA_INPUT(Eliminate zeros to the number at the left )inside the loop for internal table and change the respective values
Regards,
Ramiz