• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
captacha

C++ -- Undinitialized Variables

9 posts in this topic

I was just writing a small program today converting csv files to xml, and I noticed something weird was happening. I had an array of doubles that was being iniatialized near the end of the program using an array of strings, [font=courier new,courier,monospace]atof()[font=arial,helvetica,sans-serif], and a for loop. When I commented out the initialization and left only the declaration, I got some runtime errors. Then when I commented out the declaration, the program ran fine again. I've never had this happen to me before, so I made a short test program. All it was was an integer declaration, and it ran fine. Any idea what's causing this?[/font][/font]
0

Share this post


Link to post
Share on other sites
When your program relies on undefined behaviour, changing the generated code or the runtime memory layout, even in an unrelated areas, can suddenly reveal latent bugs elsewhere.
2

Share this post


Link to post
Share on other sites
If you are lucky, it will be the type of thing that crashes systematically. Try to find the simplest program that still has the crash, and then post it here.
0

Share this post


Link to post
Share on other sites
[CODE]
#include <iostream>
#include <string>
#include <cstdio>
#include <cstdlib>
using namespace std;
const int CELLS_IN_GRID = 81;
int main()
{
FILE *file; /* Pointer to File */

double cellValue[CELLS_IN_GRID]; /* Array of cellValues for each Cell in Grid */
string csvValue[CELLS_IN_GRID]; /* Array of cellValues as Strings */

char currentChar; /* Current Character in File Stream */
int cellPosition = 0;

string filename;
cin >> filename;

file = fopen(filename.c_str(), "r");

while(currentChar != EOF)
{
currentChar = fgetc(file);

if(currentChar != ',' && currentChar != '%')
{
csvValue[cellPosition] += currentChar;
}


if(currentChar == ',')
{
cellPosition++;
}
}

fclose(file);

/*for(int i=0;i<CELLS_IN_GRID;i++)
{
//cellValue[i] = atof(csvValue[i].c_str());
//cout << csvValue[i] << '%' << " " << i << endl;
}*/

return 0;
}
[/CODE]
Here's the code. The line that causes it to break(if commented out) is the first line in the for loop. Edited by Captacha
0

Share this post


Link to post
Share on other sites
Can you not reproduce the problem without reading an external file? Can you give us a sample external file to reproduce the problem?
0

Share this post


Link to post
Share on other sites
Also, initialise currentChar to a value != EOF. That could potentially skip your reading loop.

Check if cellPosition gets >= CELLS_IN_GRID. If it does you're writing in memory that is not yours. Once that happens all kind of weird things can happen (hence undefined).
The lines inside the for loop look ok.
2

Share this post


Link to post
Share on other sites
This is how I typically make a loop for reading from a file:
[code] while (reading statement succeeds) {
// ...
}[/code]

In the case of reading character by character (which perhaps you should reconsider), it looks like this:
[code] while ( (currentChar = fgetc(file)) != EOF) {
// ...
}[/code]
0

Share this post


Link to post
Share on other sites
Well, you also had fragile code that couldn't detect that mistake in the file. Proper error handling is tedious and hard to learn, but it's very important, so you should take this opportunity to practice by making your code detect anything that could be wrong with the file.
1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0