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Need some C++ help

Hey guys...writing a program (or, trying to;)) for my CS class...I have it about 99% done, but I can't get one nagging detail right.

What I need to do is read data from a file into parallel arrays, which are declared as:

Code:

string Brand[MAX_COMPUTER];

short RAM[MAX_COMPUTER];

where MAX_COMPUTER is a global constant. Ok. Now, the file can have any number of entries in it, including 0 to >MAX_COMPUTERS. I need to read up to and including the first MAX_COMPUTERS entries (each entry is on a new line) and nothing past that. However, I still need to accumulate a counter for entries > MAX_COMPUTER.

I tried something like:

Code:

{

short count = 0;

//open file

//check for proper opening

//file input stream is fin

fin >> Brand[count] >> RAM[count]

while (fin)

{

     count++;

     if (count <= MAX_COMPUTERS)

     {

           fin >> Brand[count] >> RAM[count];

      }

}

fin.close();

return count;

}

Works fine for a file up to MAX_COMPUTERS, but throws Memory Access Violations for entries > MAX_COMPUTERS.

Any ideas? So close to done...

Thanks in advance.

PS: If anyone wants to whole code, just to see what I'm doing, I'll put it online.

Also, if you need to understand the problem more, or I don't explain it clearly enough, you can read about it at http://www.cs.uky.edu/~ryan/CS215_F07/programs/1pgm.html

Not sure, but I'm thinking check your array index limits at this point.

Got it figured out. What was happening with the original loop is that the variable count, declared as a short, would keep counting after reading the 10 entries from the file because, since it isn't entering the IF loops, it's not actually _reading_ from the file, so it continues forever. Actually, it continues until "count" reaches 32767, which is the upper limit of a short, then it rolls over to some negative value (-1 I think) and crashes the program with Memory Access Violations. Am now using "unsigned short count = 0" since the value of count since the value shouldn't ever go negative. Also, have the loop fixed. It is now:

Code:

unsigned short count = 0;

fin.open(filename.c_str());

//file checking is done here, no reason to show it



//priming read

fin >> Brand[count] >> RAM[count];



while (fin)

{

     count++;

     if (count < MAX_COMPUTER)

     {

           fin >> Brand[count] >> RAM[count];

     }

     else 

     {

           break;

     }

}

//close files, cleanup

return count;

}

Much thanks to my Brother in Law for pointing out that I'm a dolt:-D

I was just going to point out the logical error with your bounds check, which you've fixed. Not knowing how big MAX_COMPUTER was, I don't think I would have caught the other problem.

Ah, I do recall the good old days. Now I code in Ruby, where I don't have to worry about variable declarations. :)

Um, anyone know how to control a Bubble Sort algorithm with a bool flag?

Code:

if (choice == 1)

        {

                //same comments from sort_array apply here

                for (unsigned short x = 0; x <= computer_count; x++)

                {

                        for (unsigned short j = 0; j < computer_count - 1; j++)

                        {

                                if (computer[j].Brand > computer[j+1].Brand)

                                {

                                        //This method of swapping is MUCH nice than using multiple arrays

                                        compdef temp; //create temporary struct

                                        temp = computer[j+1]; //copy entire struct

                                        computer[j+1] = computer[j];

                                        computer[j] = temp;

                                        //swap values around

                                }

                        }

                }

So that code like that would exit when there are no more swaps, instead of brute force going through all the iterations of the outer FOR loop?

Oh god, I'm going back decades (before C, much less ++ :)), so I can't offer specifics. In general, if you can't use an expression such as "Do while BooleanFlag = False", or something similar, you can simply set up an outer "If" loop:

Swapped = False
If Swapped = False
....your existing If loop logic...
Swapped = True (when the swap is made...this should terminate the outer loop)

Sorry I don't know C++, and my programming skills are rusty, but maybe this will get you thinking in the right direction...

edited: sorry, I lose my indentations on the looping logic...hope it's still clear as mud:)