The Big Programming Thread - Page 338

On August 10 2013 01:08 Ilikestarcraft wrote:
Have a quick question

In this code

while (*s++ = *t++);

I know that its copying a string but what confuses me is how does the loop actually work without what it seems to me a test condition?

#define NULL 0

On August 10 2013 01:50 spinesheath wrote:

As a sidenote: Don't write code like that. It's not readable and prone to mistakes.

This works in C/C++ because everything can and will be implicitly casted to bool. 0 => false, everything else => true. I doubt C++ would still support this if it wasn't for compatability (with C) reasons. NULL is defined as

#define NULL 0

and personally I don't like using NULL anyways, 0 does the job and doesn't have to worry about #define shenanigans.

It wouldn't work in languages with stricter typing, where you typically don't have this implicit cast to bool.

On August 08 2013 13:16 Millitron wrote:
Alright, my google-fu has failed me, I'm pretty stumped on this one.

I'm trying to use Java to create a simple coordinate plane in an image file. Basically I want a jpeg that looks like graph paper.

I can't simply grab one off google images because I don't know exactly what size I need yet or how big each grid will be, and I'd like to be able to change these easily.

My current code is as follows:

import java.awt.image.*;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import java.awt.Color;


public class BlankMapBuilder {

	/**
	 * @param args
	 * @throws IOException 
	 */
	public static void main(String[] args) throws IOException 
	{
		File mapfile = new File("blankmap.bmp");
		BufferedImage image = ImageIO.read(mapfile);
		Color c = Color.BLACK;
		for (int i = 1; i < 2000; i++)
		{
			for (int j = 1; j < 2000; j++)
			{
				if((j % 10 == 0) || (i % 10 == 0))
				{
					System.out.println("j: " + j + "i: " + i);
					image.setRGB(j, i, c.getRGB());
				}
			}
		}
	}
}

I've got a blank bitmap image of the right size and name in the package in eclipse, and the print statement triggers exactly as it should. I get no exceptions thrown or anything like that. But the image is still blank after I run the code. "image.setRGB()" doesn't seem to be doing anything.

for (int i = 10; i < 2000; i += 10)