Find user exit based on the transaction code

tables: tstc, "sap transaction codes (SAP transaction Code )
tadir, "Directory of repository objects (directory of the resource library object)
modsapt," sap enhancements-short texts (SAP enhancement-short files)
modact, "modifications (amendment)
trdir, "system table trdir (System Table trdir)
tfdir," function module (function module)
enlfdir, "Additional attributes for function modules (additional attributes of the function module)
tstct. "transaction code texts (transaction code text)

Data: jtab like tadir occurs 0 with header line.
Data: field1 (30 ).
Data: v_devclass like tadir-devclass.

Selection-screen begin of block A01 with frame title text-001.
Selection-screen Skip.
Parameters: p_tcode like tstc-tcode obligatory.
Selection-screen Skip.
Selection-screen end of block A01.

Start-of-selection.
Select single * From tstc where tcode EQ p_tcode.
If sy-subrc EQ 0.
Select single * From tadir
Where pgmid = 'r3tr'
And object = 'prog'
And obj_name = tstc-pgmna.

Move: tadir-devclass to v_devclass.
If sy-subrc Ne 0.
Select single * From trdir
Where name = tstc-pgmna.
If trdir-subc EQ 'F '.
Select single * From tfdir
Where pname = tstc-pgmna.
Select single * From enlfdir
Where funcname = tfdir-funcname.
Select single * From tadir
Where pgmid = 'r3tr'
And object = 'fugr'
And obj_name = enlfdir-area.
Move: tadir-devclass to v_devclass.
Endif.
Endif.

Select * From tadir
Into Table jtab
Where pgmid = 'r3tr'
And object = 'smod'
And devclass = v_devclass.
Select single * From tstct
Where sprsl EQ sy-Langu
And tcode EQ p_tcode.

format color col_positive intensified off.
write:/(12) 'transaction code-',
13 (20) p_tcode,
34 (10)' function -',
45 (50) tstct-ttext.
Skip.
if not jtab [] is initial.
write:/(95) sy-uline.
format color col_heading intensified on.
write:/1 sy-vline,
2 'exit name',
21 sy-vline,
22 'description ',
95 sy-vline.
write:/(95) sy-uline.

loop at jtab.
select single * From modsapt
where sprsl = sy-Langu and
name = jtab-obj_name.
format color col_normal intensified off.
write:/1 sy-vline,
2 jtab-obj_name hotspot on,
21 sy-vline,
22 modsapt-modtext,
95 sy-vline.
endloop.

Write:/(95) sy-uline.
Describe table jtab.
Skip.
Format color col_total intensified on.
Write:/'number of user exits: ', Sy-tfill.
Else.
Format color col_negative intensified on.
Write:/(95) 'This tcode has no user exit! '.
Endif.
Else.
Format color col_negative intensified on.
Write:/(95) 'the transaction Code does not exist! '.
Endif.

At line-selection.
Get cursor field field1.
Check field1 (4) eq 'jtab '.
Set parameter ID 'mon' field sy-lisel + 1 (10 ).
Call transaction 'smod and skip first screen.