DKC Atlas Forum

Here's a topic where you can discuss programming - coding styles, semantics, etc.

In general I'm most experienced with C++, next to a little Visual Basic.

Yea I was thinking on creating a topic like this to post random bits of code to help myself remember.

As for posting strings.... I was being a little silly in the code I posted in the random thought topic. . I know the correct way is:

Char string[] = {"This is a string"};

There's also no string type in c++.

In your example that's a string constant and the compiler creates a string table for things like that. char* just points to that string table. And the cout statment ignores spaces which is why you need a for loop. But i'm a total beginer and still reading that book. Classes look really interesting but it hasn't covered that yet.

C++ Beginier's Guide.

Why did you remove your post?

by the way I thnk you need to recheck your code in the random thoughts topic.

Well, I don't want to flood this topic with details on DELTA...

I'll probably repost it or something in the DKCLB topic. I realized that the post would have fit there more than in this topic.

This is my first true c++ program. I had to give myself a pat on the back. I did this all from memory and did not use the online book for help.

This program sorts an array of letters in correct alphabetical order.

Code: Select all

#include "stdafx.h"
#include <iostream>
#include <cstring>
using namespace std;

int main()
{
   char str[] = "ishpcm";
   int left = 0; int right; char x;

   for(left = 0; left <= strlen(str)-1; left++)
   {
      for(right = strlen(str)-1; right > left; right--)
      {
         if(str[right] <= str[left])
         {
            char x = str[left];
            str[left] = str[right];
            str[right] = x;
         }
      }
   }
   cout << str << "\n";
}



I'm not sure if there are any mistakes in the code but the program seems to work.

This topic feels kinda lonely. I doubt there are many programmers here.

Here's a useful little routine that I found somewhere on the internet. Might be useful for DKCLB later on.

// Fast Integer Square-Root Routine:

I can't remember who made this or where I got the function from, but I do remember it took an awful lot of digging around to find.

^ If I remember correctly operating on the individual bits of a variable is supposed to be faster then other methods. I'm assuming that's why you went looking for it as there is built in sqrt() library function.

Yeah, and I also wanted a square root function that worked with integers, because DELTA's physics system uses "fixed-point" integer math. Converting to double and back would make the operation slow. So I figured I may as well find a fast way of doing integer square roots.

Heres a question for you Simion if you can pull yourself away from DELTA

I wrote this program that searches for words in a text file and it works fine except for one thing... I am using the new function to dynamically create an array of characters which is used for the search. It works fine but when ever I try to delete it using the delete function the program hangs. I have tried to put the delete function in different areas of the program but still with no success.

Got any ideas? Below is the code and cpp file. And yes there is a lot of redundency in the comments.

Edit: Attachments are broken?

Code: Select all

   char *search= new char[]; // or use a pointer to a new array of unknown size.
   char yn[100]; // Store the yes\no answer in a character array.

You've got to define the size when using new, you can't new an unknown size. Generally it should be:



Also, I'd like to mention that doing:
---is not the same thing as---

The first one is always a char*, no matter how many array dimensions you use. The second is pointer to array of char*.

Thanks, I kinda figured the unsized array was the problem. I did try the sized array which if you noticed was commented out. What prevented the sized array from working was the function gets() . To fix I used getline() instead.

Is there any reason in particular you specified the size of the array using a hex value?

Cyclone wrote:Thanks, I kinda figured the unsized array was the problem. I did try the sized array which if you noticed was commented out. What prevented the sized array from working was the function gets() . To fix I used getline() instead.

Is there any reason in particular you specified the size of the array using a hex value?

He is probably just used to coding that way for DELTA as fixed-point notation is easier to understand in hex then values.

This was the slice of code that I never did post in the DELTA topic, because it's now unused due to my finding out about MMX and using inline assembly instead (which by the way is several orders of magnitude faster than raw C++).

I finally found this thing again in a random text file and thought I'd post it for all to see.


What this does is add together two RGB pixels, saturating the values at 255 if the addition overflows. All done without conditional jumps. The only catch is that the alpha value will probably get clobbered in the process (which was by design).

The same thing in MMX assembly is roughly: