C++ question

Hi all
here I have a c++ question (decoding the encoding text file message) where I need to design a program which should do the following:


(a) read text from a file and calculate the number and percentage of occurrences of each letter in that file;

(b) find for each letter in the encoded message which alphabet letter it represents, using the frequency analysis of the training and encoded text as well as interactive input/output with the user.

(c) substitute the letters in the encoded message for letters they represent and output the decoded message into some file.

I need the user to be abale to repeat the stpes as many times as required.

also:

(d) Test your programme. Provide sufficient evidence of testing.

(e) Implement a simple option menu to make your program easier to use.
-Sequential menu
-Hierarchical menu

(f) Improve your programme. Consider cases such as choosing an option that is not available in the menu, starting from option 2,3, etc. instead of 1, etc.

the porogram should match the following requirements as well:
1- using call by reference

2- using global variables

3- using functions which contain pre and post conditions

4- error message should appear in the following cases:
- if the file was not opened successfully.
- Menu - choosing option not available
-any other cases? please state?

5- Names of the files are interactively given by the user?

6- Interactive input/output of letter substitutions?



kind of decomentation (algorithms) is required which should include:
1- step by step description

2- flowcharts

3- Graphical representation of the menu (also, number of options and levels in the menue)

4- evidence of testing in the decomentaion and number of tests

5- Limitations and improvements?



I have attached the encoded message and the deadline should be on Monday, 12-12-2011

waiting for help and reasonable prices