The Big Programming Thread - Page 146

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Thread Rules
1. This is not a "do my homework for me" thread. If you have specific questions, ask, but don't post an assignment or homework problem and expect an exact solution.
2. No recruiting for your cockamamie projects (you won't replace facebook with 3 dudes you found on the internet and $20)
3. If you can't articulate why a language is bad, don't start slinging shit about it. Just remember that nothing is worse than making CSS IE6 compatible.
4. Use [code] tags to format code blocks.

green.at

Austria1459 Posts

June 23 2012 20:00 GMT

#2901

does anyone have experience with multi-agent development, especially with JADE? If so, do you know how to connect directly to another platform over the net?

ranshaked

United States870 Posts

June 24 2012 03:03 GMT

#2902

On June 22 2012 07:00 Abductedonut wrote:

Show nested quote +

I whipped up some quick code for you. It's by no means pretty. Here you go. Assuming you're using C, same principles should apply in C++. Next time, specify which language you use!

+ Show Spoiler +


#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[]
{
  int randomNum = 0, randomNum2 = 0, mathOperator = 0;
  float result = 0, answer = 0;
  srand ( time(NULL) );
  
  char map[4] = {'-','+','*','/'};
  
  while( 1 )
  {
      randomNum = rand()%100; //Truncated it to a limit of 100, so that you don't get ridiculous numbers...
      printf("%i ",randomNum);
      mathOperator = rand()%4; 
      printf("%c ",map[mathOperator] );
      randomNum2 = rand()%100;
      printf("%i",randomNum2);
      
      switch ( map[mathOperator] )
      {
             case '-':
                  result = randomNum - randomNum2;
                  break;
             case '+':
                  result = randomNum + randomNum2;
                  break;
             case '*':
                  result = randomNum * randomNum2;
                  break;
             case '/':
                  result = (float)randomNum / ( (float)randomNum2 );
                  printf(" Result is: %f ",result);
                  break;
      }
      
      //How come the divison never works??
      //It's because of round-off errors within the computer. Trying looking at:
     //http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
      printf(" \nWhat is the answer? ");
      scanf("%f",&answer);
      printf("you entered: %f \n",answer);
      fflush(stdin);
      
      if ( answer == result )
         printf("Correct! \n");
  }
  
  return 0;
}

The basic idea between comparing floats is that you must have a general "error" range that you're okay with.

Most floats, when printed, will get rounded off. So it may seem like the answer is 1.3333334 but in memory its actually stored as 1.333333333333333333333. So when you do the comparison, it gets jacked up. Read the article I commented in the code.

Also, does anyone have expierence with Microsoft's Media Foundation? I've been trying to use MF to capture to a hwnd using D3D and I'm having a really hard time. Would appreciate any help.

Thanks. I've tried using %.2f to limit it, %f, %lf and it's always random, some division problems will read my answers properly, and some won't. I marked the two that are not are opposite

Edit: I'm reading that you cannot directly compare floats :/ unless you use a function, but unfortunately I was never taught this!

Edit again: This happens with both your code, and my original "if" statements. The problem is this: If it's not division, the answer has to be an integer, but if it's division it has to be two decimal places, like 2.12...

When you're casting floats or doubles with (double) x / ((double)y) can you cast that directly to two decimal places? Like doing (double.2)x ?

Abductedonut

United States324 Posts

June 24 2012 03:54 GMT

#2903

On June 24 2012 12:03 ranshaked wrote:

Show nested quote +

On June 22 2012 07:00 Abductedonut wrote:

On June 22 2012 06:12 ranshaked wrote:
I'm typing from my phone, so please bare with me. I had an assignment that I handed in that was not complete because I could not figure out how to do division. Basically the assignment is like this:
Randomly generate a math sign (+*/-) and two random numbers and ask the user to solve the problem. Everything works properly except the division. I know that it is because I'm using integers, but when I caste them as floats in my if or switch statements (tried both) it either gets 0.000000 all the time or it messes up the other integers. The final line needs to print the answer. Because it is random, I'm struggling with the final answer, everything will wok except division

I'll post the code later. Thanks

I whipped up some quick code for you. It's by no means pretty. Here you go. Assuming you're using C, same principles should apply in C++. Next time, specify which language you use!

+ Show Spoiler +


#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[]
{
  int randomNum = 0, randomNum2 = 0, mathOperator = 0;
  float result = 0, answer = 0;
  srand ( time(NULL) );
  
  char map[4] = {'-','+','*','/'};
  
  while( 1 )
  {
      randomNum = rand()%100; //Truncated it to a limit of 100, so that you don't get ridiculous numbers...
      printf("%i ",randomNum);
      mathOperator = rand()%4; 
      printf("%c ",map[mathOperator] );
      randomNum2 = rand()%100;
      printf("%i",randomNum2);
      
      switch ( map[mathOperator] )
      {
             case '-':
                  result = randomNum - randomNum2;
                  break;
             case '+':
                  result = randomNum + randomNum2;
                  break;
             case '*':
                  result = randomNum * randomNum2;
                  break;
             case '/':
                  result = (float)randomNum / ( (float)randomNum2 );
                  printf(" Result is: %f ",result);
                  break;
      }
      
      //How come the divison never works??
      //It's because of round-off errors within the computer. Trying looking at:
     //http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
      printf(" \nWhat is the answer? ");
      scanf("%f",&answer);
      printf("you entered: %f \n",answer);
      fflush(stdin);
      
      if ( answer == result )
         printf("Correct! \n");
  }
  
  return 0;
}

Thank you very much, it definitely helped. Would also happen to know why when I type in an answer to a division problem exactly the way I printf the answer, that it still doesn't read it in as correct? Basically this is what is happening: I'll post an image. I have it set to debug in which it gives me the answer, then I type in the answer and it should say "correct!", but for some reason, I type in EXACTLY what it prints out the answer to be, and it's still reading it as wrong. Here's an image.

Thanks. I've tried using %.2f to limit it, %f, %lf and it's always random, some division problems will read my answers properly, and some won't. I marked the two that are not are opposite

Edit: I'm reading that you cannot directly compare floats :/ unless you use a function, but unfortunately I was never taught this!

Edit again: This happens with both your code, and my original "if" statements. The problem is this: If it's not division, the answer has to be an integer, but if it's division it has to be two decimal places, like 2.12...

When you're casting floats or doubles with (double) x / ((double)y) can you cast that directly to two decimal places? Like doing (double.2)x ?

You're thinking of it the wrong way. How you PRINT decimals to the screen and how the computer actually stores them are two completely different things. When you use printf, cout, whatever output you use, those functions are written to take the value inside the computer and print it in a way you specify. The printf family of functions doesn't particularly care if the value inside the computer is 2.999999999 or 3.0000000001. It will print out 3 if specify it to one digit.

Now when you do a comparison inside your program, such as:

if ( float1 == float2 )

Then the computer assumes that they must be the same at EVERY SINGLE DECIMAL SPACE PAST THE DECIMAL POINT. So as a concrete example, if float1 = 1.9999999999999999 and float2 = 1.9999999999999998 then as far as the computer is concerned, they are not equal. Whoops, your above if statement would fail. That is why floats need an acceptable margin for error. To you, float1 and float2 are pretty much the same. I mean, who cares about the 10th or 11th decimal place not being the same, right?

That is why the more LOGICAL equivalent for the comparison above is like this:

if ( ABSOLUTEVALUE( float1 - float2 ) <= 0.000000000001 )

This above comparison basically says "okay look, if these floats are the same up till this decimal point, then I pretty much consider them equal."

Well guess what? Everytime you call scanf, the value the user puts in, such as 1.24, it can actually get stored as 1.2399999999999999999999999. That is precisely why your program is failing, and that is precisely what that exercise is supposed to teach you. Here's working code, in case you need an even more concrete example:

+ Show Spoiler +

Here are some of the results when you run the code in the spoiler:
43 / 3 Result is: 14.33
What is the answer? 14.33
you entered: 14.3299999237
But trancted to two decimal places.. you entererd: 14.33
Correct!
50 / 4 Result is: 12.50
What is the answer? 12.50
you entered: 12.5000000000
But trancted to two decimal places.. you entererd: 12.50
Correct!
89 / 96 Result is: 0.93
What is the answer? 0.93
you entered: 0.9300000072
But trancted to two decimal places.. you entererd: 0.93
Correct!
38 / 44 Result is: 0.86
What is the answer? 0.86
you entered: 0.8600000143
But trancted to two decimal places.. you entererd: 0.86
Correct!
60 / 8 Result is: 7.50
What is the answer?

+ Show Spoiler +


#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[] )
{
  int randomNum = 0, randomNum2 = 0, mathOperator = 0;
  float result = 0, answer = 0;
  srand ( time(NULL) );
  
  char map[4] = {'-','+','*','/'};
  
  while( 1 )
  {
      randomNum = rand()%100; //Truncated it to a limit of 100, so that you don't get ridiculous numbers...
      printf("%i ",randomNum);
      mathOperator = 3; 
      printf("%c ",map[mathOperator] );
      randomNum2 = rand()%100;
      printf("%i",randomNum2);
      

      result = (float)randomNum / ( (float)randomNum2 );
      printf(" Result is: %.2f ",result);
      
      printf(" \nWhat is the answer? ");
      scanf("%f",&answer);
      printf("you entered: %.10f \n",answer);
      printf("But trancted to two decimal places.. you entererd: %.2f \n",answer);
      fflush(stdin);
      
      
      if ( map[mathOperator] == '/'  && ( (answer-result) <= 0.001 || result-answer <= 0.001) )
         printf("Correct! \n");
  }
  
  return 0;
}

ranshaked

United States870 Posts

June 24 2012 04:03 GMT

#2904

On June 24 2012 12:54 Abductedonut wrote:

Show nested quote +

On June 24 2012 12:03 ranshaked wrote:

On June 22 2012 07:00 Abductedonut wrote:

I whipped up some quick code for you. It's by no means pretty. Here you go. Assuming you're using C, same principles should apply in C++. Next time, specify which language you use!

+ Show Spoiler +


#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[]
{
  int randomNum = 0, randomNum2 = 0, mathOperator = 0;
  float result = 0, answer = 0;
  srand ( time(NULL) );
  
  char map[4] = {'-','+','*','/'};
  
  while( 1 )
  {
      randomNum = rand()%100; //Truncated it to a limit of 100, so that you don't get ridiculous numbers...
      printf("%i ",randomNum);
      mathOperator = rand()%4; 
      printf("%c ",map[mathOperator] );
      randomNum2 = rand()%100;
      printf("%i",randomNum2);
      
      switch ( map[mathOperator] )
      {
             case '-':
                  result = randomNum - randomNum2;
                  break;
             case '+':
                  result = randomNum + randomNum2;
                  break;
             case '*':
                  result = randomNum * randomNum2;
                  break;
             case '/':
                  result = (float)randomNum / ( (float)randomNum2 );
                  printf(" Result is: %f ",result);
                  break;
      }
      
      //How come the divison never works??
      //It's because of round-off errors within the computer. Trying looking at:
     //http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
      printf(" \nWhat is the answer? ");
      scanf("%f",&answer);
      printf("you entered: %f \n",answer);
      fflush(stdin);
      
      if ( answer == result )
         printf("Correct! \n");
  }
  
  return 0;
}


#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[] )
{
  int randomNum = 0, randomNum2 = 0, mathOperator = 0;
  float result = 0, answer = 0;
  srand ( time(NULL) );
  
  char map[4] = {'-','+','*','/'};
  
  while( 1 )
  {
      randomNum = rand()%100; //Truncated it to a limit of 100, so that you don't get ridiculous numbers...
      printf("%i ",randomNum);
      mathOperator = 3; 
      printf("%c ",map[mathOperator] );
      randomNum2 = rand()%100;
      printf("%i",randomNum2);
      

      result = (float)randomNum / ( (float)randomNum2 );
      printf(" Result is: %.2f ",result);
      
      printf(" \nWhat is the answer? ");
      scanf("%f",&answer);
      printf("you entered: %.10f \n",answer);
      printf("But trancted to two decimal places.. you entererd: %.2f \n",answer);
      fflush(stdin);
      
      
      if ( map[mathOperator] == '/'  && ( (answer-result) <= 0.001 || result-answer <= 0.001) )
         printf("Correct! \n");
  }
  
  return 0;
}

Thank you, this is much easier to understand than the things I've been reading. I understand now, I assumed that by using a float it automatically limited the answer to only 6 decimal places, I didn't realize that even though it doesn't show, it's still checking down the line.

I will try this and let you know. This stuff is fascinating, and challenging. I dislike how I've been stuck on this all day, but i'll play with it now. I actually enjoy spending hours trying to figure stuff out and playing with it, but sometimes I get stuck like this!

Abductedonut

United States324 Posts

June 24 2012 04:19 GMT

#2905

On June 24 2012 13:03 ranshaked wrote:
Thank you, this is much easier to understand than the things I've been reading. I understand now, I assumed that by using a float it automatically limited the answer to only 6 decimal places, I didn't realize that even though it doesn't show, it's still checking down the line.

I will try this and let you know. This stuff is fascinating, and challenging. I dislike how I've been stuck on this all day, but i'll play with it now. I actually enjoy spending hours trying to figure stuff out and playing with it, but sometimes I get stuck like this!

No problem. That's what this thread is for! Here's another really creative way you could have solved this problem, btw.

I feel like you'd like this.



#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

int main(int argc, char *argv[] )
{
  int randomNum = 0, randomNum2 = 0, mathOperator = 0;
  float result = 0, answer = 0;
  srand ( time(NULL) );
  
  char map[4] = {'-','+','*','/'};
  char cool1[10], cool2[10];
  
  while( 1 )
  {
      randomNum = rand()%100; //Truncated it to a limit of 100, so that you don't get ridiculous numbers...
      printf("%i ",randomNum);
      mathOperator = 3; 
      printf("%c ",map[mathOperator] );
      randomNum2 = rand()%100;
      printf("%i",randomNum2);
      

      result = (float)randomNum / ( (float)randomNum2 );
      
      sprintf(cool1,"%.2f",result);
      printf(" Your answer: ");
      scanf("%f",&answer);
      sprintf(cool2,"%.2f",answer);
      fflush(stdin);
      
      if ( !strcmp(cool1,cool2) )
         printf("Correct! \n");
         
  }
  
  return 0;
}

Ghad

Norway2551 Posts

June 24 2012 21:21 GMT

#2906

The official Video Torrent from NDC Oslo 2012 with 87 gigs of free development videos is now up. You are welcome.

http://www.ndcoslo.com/Article/News/2012video

Iwbhs

United States195 Posts

June 25 2012 00:12 GMT

#2907

http://pastebin.com/myhvzy1q

Any idea on why my tooltip breaks when I include html?

berated-

United States1134 Posts

June 25 2012 00:19 GMT

#2908

On June 25 2012 09:12 Iwbhs wrote:
http://pastebin.com/myhvzy1q

Any idea on why my tooltip breaks when I include html?

Looks like you need to escape your quotes.

onmouseover="doStuff(\"escape me \")"

Iwbhs

United States195 Posts

June 25 2012 00:22 GMT

#2909

<div id="shoulder" ONMOUSEOVER="ddrivetip('1 Armor<br /><a href="/class.php?c=Monk&d=Shoulder">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1<br />','black')"; ONMOUSEOUT="hideddrivetip()" style="background-image: url(images/Shoulder.png);"></div>

where is the mistake in quotes?

<div id="shoulder" ONMOUSEOVER="ddrivetip('1 Armor<br /><a href=\"/class.php?c=Monk&d=Shoulder\">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1\n','black')"; ONMOUSEOUT="hideddrivetip()" style="background-image: url(images/Shoulder.png);"></div>

not working.

berated-

United States1134 Posts

June 25 2012 00:45 GMT

#2910

On June 25 2012 09:22 Iwbhs wrote:

<div id="shoulder" ONMOUSEOVER="ddrivetip('1 Armor<br /><a href="/class.php?c=Monk&d=Shoulder">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1<br />','black')"; ONMOUSEOUT="hideddrivetip()" style="background-image: url(images/Shoulder.png);"></div>

where is the mistake in quotes?

<div id="shoulder" ONMOUSEOVER="ddrivetip('1 Armor<br /><a href=\"/class.php?c=Monk&d=Shoulder\">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1\n','black')"; ONMOUSEOUT="hideddrivetip()" style="background-image: url(images/Shoulder.png);"></div>

not working.

yeah mental lapse, you can't use \ in html, you would have to escape it using html ". The best way to avoid this is probably restructure your code a little bit, but thats a different argument.

To get it working pick one quote for the outside and one for the inside, what I mean by that is..

<div id="shoulder" ONMOUSEOVER='ddrivetip("1 Armor<br /><a href=\"/class.php?c=Monk&d=Shoulder\">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1\n","black");' ONMOUSEOUT="hideddrivetip()" style="background-image: url(images/Shoulder.png);"></div>

You also have to escape the quote for the js

Edit: Yeah okay this is painful a couple questions...

1) Is there any reason you aren't using jquery?

2) Even if you aren't using jquery you can still accomplish this. It would probably be cleaner if you hid the html that you wanted to use in a div somewhere on the page and then grabbed it load the tip.

Example: ( I didn't test this, just trying to show the general concept )

<div id="shoulder" ONMOUSEOVER="ddrivetip('tooltiptext','black');" ONMOUSEOUT="hideddrivetip()" style="background-image: url(images/Shoulder.png);"></div>


<div id="tooltiptext" style="display:none">
1 Armor<br /><a href="/class.php?c=Monk&d=Shoulder">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1
</div>


function ddrivetip(theid, thecolor, thewidth){
	if (typeof thewidth!="undefined") tipobj.style.width=thewidth+"px"
	if (typeof thecolor!="undefined" && thecolor!="") tipobj.style.backgroundColor=thecolor
	tipobj.innerHTML=document.findElementById(theid).innerHTML
	enabletip=true
	return false
}

3FFA

United States3931 Posts

June 25 2012 01:24 GMT

#2911

I'm starting to learn programming today with Java. I am being taught the basics by my older brother and he gave me a program to use called Eclipse. Is there any good tips I could get for someone starting out learning Java? Has anyone used Eclipse before? I also am testing myself as I learn with codingbat.com. Is there any other sites like that for Java? Do note that I didn't read the thread other than the OP. Sorry for that.

tofucake

Hyrule19153 Posts

June 25 2012 01:30 GMT

#2912

Eclipse is pretty standard for Java. Unfortunately it's got a lot of features you'll probably not use which slow it down considerably. Just poke around some tutorials. Buy a Java book if you're serious about learning Java. If you're like me (learn by doing), I suggest a mid level book rather than a For Dummies or whatever. Check this out

3FFA

United States3931 Posts

June 25 2012 01:37 GMT

#2913

Ok thanks a lot! Also, I will be learning C++ come September in my High School because I got the highest test grades in my class and was able to qualify for it (of course said yes immediately as I've always been interested in programming) so that led to me asking my brother if I could learn a language that he knows. My plan is to learn a good amount of Java this summer and many years down the road my plan is to make an RTS game. However, I will of course make a lot of much simpler stuff first.

I've already been told how things like a 1 instead of an i can mess up coding so much that you may spend hours asking people to help you look through it, possibly even a whole day.

Blisse

Canada3710 Posts

June 25 2012 01:43 GMT

#2914

Wait until you can't find the = that's supposed to be a == ....

-_____-"

Azerbaijan

United States660 Posts

June 25 2012 02:46 GMT

#2915

Can anyone reccomend a good book for learning C? The one I have is from the 70s.

jergason

United States37 Posts

June 25 2012 04:56 GMT

#2916

The C Programming Language is the best book on C, and one of the best programming books ever written.

http://www.amazon.com/C-Programming-Language-2nd-Edition/dp/0131103628/ref=sr_1_1?ie=UTF8&qid=1340600201&sr=8-1&keywords=the c programming language

supereddie

Netherlands151 Posts

June 25 2012 09:59 GMT

#2917

On June 25 2012 09:45 berated- wrote:

2) Even if you aren't using jquery you can still accomplish this. It would probably be cleaner if you hid the html that you wanted to use in a div somewhere on the page and then grabbed it load the tip.

Example: ( I didn't test this, just trying to show the general concept )

<div id="shoulder" ONMOUSEOVER="ddrivetip('tooltiptext','black');" ONMOUSEOUT="hideddrivetip()" style="background-image: url(images/Shoulder.png);"></div>


<div id="tooltiptext" style="display:none">
1 Armor<br /><a href="/class.php?c=Monk&d=Shoulder">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1
</div>


function ddrivetip(theid, thecolor, thewidth){
	if (typeof thewidth!="undefined") tipobj.style.width=thewidth+"px"
	if (typeof thecolor!="undefined" && thecolor!="") tipobj.style.backgroundColor=thecolor
	tipobj.innerHTML=document.findElementById(theid).innerHTML
	enabletip=true
	return false
}

Even easier is just use CSS.


<style type="text/css">
.tooltiptext{ display: none; position: fixed; top: 0; right: 0; }
.tt:hover .tooltiptext{ display: block; }
</style>

...

<div class="tt" id="shoulder" style="background-image: url(images/Shoulder.png);">
 <div class="tooltiptext">
  1 Armor<br /><a href="/class.php?c=Monk&d=Shoulder">Shoulder</a><br />&nbsp;&nbsp;&nbsp;All Resistance: 1
 </div>
</div>

Ofcourse, this won't work in Internet Explorer < 8, but it works in any recent browser so who cares?

Poltergeist-

Sweden336 Posts

June 25 2012 10:10 GMT

#2918

What are the latest and greatest/upcoming programming languages, if any? Anyone have any idea? Does it differ possibly between the US and EU?

Joefish

Germany314 Posts

June 25 2012 17:03 GMT

#2919

On June 25 2012 19:10 Poltergeist- wrote:
What are the latest and greatest/upcoming programming languages, if any? Anyone have any idea? Does it differ possibly between the US and EU?

According to this website, the top 3 are C/Java/C++.
And I don' think there is any difference between different regions. But haven't found any data about it.
I'm actually surprised C being at the top of the charts. Thought top 3 would look like this C++/Java/PHP.

Isualin

Germany1903 Posts

June 25 2012 17:13 GMT

#2920

any idea why C is getting bigger? isn't it quite old?

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