Hello Stefano,

I was checking some features of FLAP and it's a great tool, i'm sure that will be useful for us :)

Through flap_test, I have seen that in some lines when a logical is expected by FLAP there is no error handling. For example if you runl flap_test with the following arguments an error arises:

$ flap_test/FLAP_TEST -s 'asdf' --boolean_val 0
+--> flap_test, a testing program for FLAP library
+--> Parsing Command Line Arguments
forrtl: severe (59): list-directed I/O syntax error, unit -5, file Internal List-Directed Read
...
FLAP_TEST 0000000000411D54 data_type_command 289 ...
...

The error references the following line:
https://github.com/szaghi/FLAP/blob/master/src/Data_Type_Command_Line_Interface.f90#L289

A proposal to handle this error might be to replace that line with:

   read(cla%val,*,iostat=error)val
   if(error) write(stderr,'(A)')prefd//' Error: cannot convert "'// &
                  trim(adjustl(cla%val))//'" of CLA "'//cla%switch//'" to boolean.'

Maybe you will find this change useful.

Best regards,
Víctor.