Keskustelu: Ohjelmointikysymykset: C++: Ehdotuksia C-harjoituksiksi

Make a C-language function.


Function is passed three parameters:

  char pointer to a string containing an extended binary coded
decimal number
  starting at the byte boundary

  int length of the above in nibbles (can be odd or 0), actual EBCD
may be
  shorter (see below)

  char pointer to null ended left justified ascii string containing
  at return the EBCD number in ascii format.

Function translates passed EBCD into ascii format. Caller must take
care that
enough room is reserved for the ascii string; overflow is not checked
inside
the function.


EBCD is defined as follows:

 - each code (number or character) takes a four bit nibble
 - four bit nibbles are consecutive in the string
 - codes 0x0 - 0x9 are translated into ascii characters '0' - '9'.
 - code 0xC is translated into ascii character '#'
 - code 0xD is translated into ascii character '*'
 - EBCD can be any length between 0 and length parameter
 - EBCD can be left justified. Then 0xF is the end marker
 - EBCD can be right justified. Then it is padded with 0xF
 - EBCD can be in the middle. Then both above rules apply
 - if EBCD is 0 length, null string ("\0") is formed for return.
 - if length parameter is 0, EBCD is considered to be 0 length.


The value of the function is char pointer. If parameters follow above
rules
pointer to ascii string is returned, else NULL pointer is returned.


Additionally make a function that generates test cases to the above
function
and a main function that calls them and prints the resulting ascii
string.


Try to make the code as simple as possible and self commenting. Add
comments
clarifying semantics where not self evident. Use semantically
descriptive
names (but not too long).