Hi,
To do this task exists a function called CONVERSION_EXIT_ALPHA_INPUT that has only one input parameter and another for the result:
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_INPUT'
EXPORTING
input = ls_selprod-Matnr
IMPORTING
output = ls_selprod-Matnr.
I have used this to fill parameters that must be passed into a BAPI.
& that's all,
Greetings.
