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[Reelya]

You get a pointer to the first element, then go to the "next" pointer for that, and so on, until you hit a null, which means end-of-list. This is just how a basic linked list works. You have a pointer for "head" and that's it, and you follow the pointers until you run out of list.

[i2amroy]

You could also just get a forward iterator to the first element and then use that to iterate.

Yeah a forward iterator is basically a standardized way to automatically handle all the for loop + this = this.next stuff without you needing to manually worry about it.

[da_nang]

Is anyone familiar with clustering algorithms?

Say I have a finite set of numbers. I want to divide this set into k partitions such that the sum of the variances of each set's consecutive differences is minimized, assuming all sets are ordered.

Is there a suitable algorithm for this? I'm thinking k-means can be modified to do this but is there a better approach?

[Elephant Parade]

Working on an assignment for my Computer Science class. For some reason, my second System.in.read() just doesn't work, and I haven't been able to fix it or figure out why.

Code: [Select]

class ConstructedPower {
    int base, exponent;
   
    ConstructedPower(int bs, int exp) {
        base = bs;
        exponent = exp;
    }
   
    double getValue() {
       
        if(exponent < 0) {
            System.out.println("ERROR: exponent below 0");
            return 0;
        }
        else return Math.pow(base, exponent);
    }
   
    double customValue() throws java.io.IOException {
        int[] baseArray = {2, 10, 16};
        int[] exponentArray = {1, 2, 4};
       
        System.out.println("INPUT BASE - A = 2, B = 10, C = 16, D = EXIT");
        char ch = (char) System.in.read();
       
        if(ch == 'A') base = baseArray[0];
        if(ch == 'B') base = baseArray[1];
        if(ch == 'C') base = baseArray[2];
        if(ch == 'D') {
            System.out.println("QUITTING");
            return 0;
        }
       
        System.out.println("INPUT EXPONENT - A = 1, B = 2, C = 4, D = EXIT");
        ch = (char) System.in.read(); // this usually doesn't trigger. why? I have no idea!
       
        if(ch == 'A') exponent = exponentArray[0];
        if(ch == 'B') exponent = exponentArray[1];
        if(ch == 'C') exponent = exponentArray[2];
        if(ch == 'D') {
            System.out.println("QUITTING");
            return 0;
        }
       
        return Math.pow(base, exponent);
    }
}

public class SanePower {
    public static void main(String[] args) throws java.io.IOException {
        System.out.println("Initializing...");
       
        ConstructedPower newPower = new ConstructedPower(2, 2);
       
        double a = newPower.getValue();
        System.out.println(a);
       
        double b;
       
        do {
            b = newPower.customValue();
            System.out.println(b);
        }
        while(b != 0);
       
    }
}
I hate to just dump a bug on the thread like this, but it's too late in the evening to contact the professor, the assignment is (weirdly) due at midnight, and I legitimately have no clue what's causing this.

edit: never mind, figured it out. I feel pretty silly now.

[Avis-Mergulus]

Ignore me.

I can do that.

...Well, shit.

[Parsely]

edit: never mind, figured it out. I feel pretty silly now.

That's normal. I just spent an hour or so reading about Twitter APIs only to find that Twitter has a function in the settings to generate the HTML for an embedded Twitter timeline for you. One copy-paste job and googling of parameters to give it the desired styling, and the goal was achieved. And it only took 5 minutes.

[sprinkled chariot]

Ehm, how are beam/laser weapons usually made codewise? 

Cant figure, how to make one, which stops upon hitting something, without everything looking awful.

 1) uninterrupting stream of small projectiles starts looking like wave emitter, if fired not in 90/180/360/0 degrees direction, unless our projectiles are 1 x 1 pixel
2) creating single object with animation and fully animated sprite bumps into the problem of having to add  several more pixels on each of  800 animation frames frames
3) just having one very long object has problem of hitting everything on its way

[Dozebôm Lolumzalěs]

You don't make them codewise, you start with a beam weapon and then you code the interface.

[miauw62]

There is no good way to answer that without any other information. Look into raycasting, maybe?

As for the sprite, can't you just have a short sprite and repeat it as many times as neccessary? Sure, you might have to cut off a little on at least one side, but it seems the best solution for something that isn't a simple gradient beam.

[Shadowlord]

You map a texture onto a "beam"of arbitrary length, or draw all pixels along a line, or...

[TheBiggerFish]

You map a texture onto a "beam"of arbitrary length, or draw all pixels along a line, or...

Exactly.

[Reelya]

For the edges use some alpha blending or anti-aliasing, too, which will make it look more laser-like or less jaggy/pixelated.

[itisnotlogical]

When you log in to public wi-fi, often there's a landing page with a button you have to press before it'll let you actually connect to the Internet. How is this done? I assume it's the local network serving its own page to a new user when it first requests something, but what is the more specific answer?

[Shadowlord]

I don't know how they do it, but I know how I would do it: Devices on a network send their MAC address in the packets they send (it isn't sent outside the network, however). Since this is a unique identifier for the network card (or equivalent), it's possible to use it to fingerprint devices on a network. This would require keeping a hashtable or the like of known mac addresses and whether they've agreed to the terms. I would expect that it would be possible to filter all network traffic by anyone who hasn't agreed and redirect them to the agreement page when they try to use a web browser.

[i2amroy]

This would require keeping a hashtable or the like of known mac addresses and whether they've agreed to the terms. I would expect that it would be possible to filter all network traffic by anyone who hasn't agreed and redirect them to the agreement page when they try to use a web browser.

Pretty much, though most of them only keep you in the list for a rather short time, (an hour or so is pretty common) and then dump you from it.

As for how they actually do it, the most common way is just intercepting all DNS requests from unauthenticated clients and repointing them at their own pages (it's basically a codified man-in-the-middle attack, set up so that it has absolute minimum impact on the network outside itself). The other way you'll sometimes see it set up is just basically by setting up an ICMP redirect that pushes all unauthorized clients onto their own page no matter where they go.