Handling exceptions is a good skill to learn as more and more functions and classes throw exceptions when things go wrong.

Process

1. Start by making a back up copies of your working

    buffer04.h

   and

    lab04main.cpp

   Just In Case. Continue working with the originals.

   By the way -- the UNIX/Linux copy command is cp and can be used like this:

    		cp buffer04.h buffer04.h.bak

2. Make sure that lab04main.cpp still compiles!
3. Add the

    #include<stdexcept>

   needed (book page 820) to both files. Include

    	using namespace std;

   Test the result with a quick recompilation and run of lab04main.cpp!
   Currently the operator[] returns '\0' when the index i is out of range. Instead make it throw out_of_range("Buffer operator[]").
4. Test main program with out changing it.
5. If needed add a new command in main program to execute

    		cout<< b[24]<<endl;

6. Run it and watch the exception get thrown.
7. In the main program add a try{...}catch(...){...} about the command that fails to catch the out_of_range exception. Here is a suggested test( page 352)

    	try{

    		assert( b[24] == '\0' );

    	}

    	catch(exception& e)

    	{

    		cerr << "Exception "<< typeid(e).name() << ": " <<  e.what();

    	}

8. In buffer04.h add a variable to count the number of discarded characters. You need two new lines

    		int discard=0;

   and

    			discard++;

   somewhere. Figure out where inside operator>>.
9. Test by compiling and running lab04main.cpp.
   Add a throw to the operator>> function in the buffer04.h so that if (discard >0) then throw a 'length_error'. Compile lab04main as is and test with short and long inputs.
10. Change lab04main so that it catches the length error and reports it to the user. Note: you should be able to catch errors in both cin>> commands with a single

     		try{...}catch(length_error&e){...}

    block. Hint: put the try{ at the start and catch(...){...} at the end of the main block.

    
    Add another throw to the operator>> function to recognize enemy action: more than 70 characters in a line. It should throw

     		runtime_error("Hacker Attacker!");

11. Test the lab04main.cpp program to be sure that it distinguishes a mistake from a likely attack. Add a catch(exception&e)... after the catch(length_error&e){...}.
12. Show me that the program runs and handles all three exceptions and earn lots of points.