Ask General Programming Questions Not Worth Their Own Thread

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Sexxxy Sophitia: Aug 28, 2008; Anime Baby

So I have to write a program to explain bytes and bits and int values in C
but I'm having trouble getting exponents to work. Here's an example of what I'm doing.

code:

printf("A long value stores %d byte(s)\n",sizeof(w));
printf("Which means it can store %d bits.\n",sizeof(w)*8);
printf("That means it can store %d values.\n",(pow(2,(sizeof(w)*8))));

Should I be doing this differently because it's returning the wrong values.

# ? Oct 30, 2008 16:22

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# ? May 14, 2024 11:39

csammis: Aug 26, 2003; Mental Institution

Sexxxy Sophitia posted:

So I have to write a program to explain bytes and bits and int values in C
but I'm having trouble getting exponents to work. Here's an example of what I'm doing.
code:
printf("A long value stores %d byte(s)\n",sizeof(w));
printf("Which means it can store %d bits.\n",sizeof(w)*8);
printf("That means it can store %d values.\n",(pow(2,(sizeof(w)*8))));
Should I be doing this differently because it's returning the wrong values.

I assume somewhere you've declared a long w, right? Try sizeof(long) instead. If it's still returning the "wrong" values, post what it is returning and we'll be able to tell you why it's right

e: Oh, only the exponent thing is wrong? What is it returning?

e2: Why would you tell us it's returning the wrong values without saying what those are in the first place?

# ? Oct 30, 2008 16:28

Sexxxy Sophitia: Aug 28, 2008; Anime Baby

The return I get is:

code:

LONG
A long value stores 4 byte(s)
Which means it can store 32 bits.
That means it can store 1106247680 values.

I can post the whole program if that would help.

csammis posted:

e2: Why would you tell us it's returning the wrong values without saying what those are in the first place?

I don't know

# ? Oct 30, 2008 16:34

ShoulderDaemon: Oct 9, 2003; support goon fund; Taco Defender

Sexxxy Sophitia posted:

code:

printf("That means it can store %d values.\n",(pow(2,(sizeof(w)*8))));

%d wants an int parameter. Even if pow returned an int instead of a double, you can't fit the number you want in an int, by definition. Replace %d in this line with %.0f and it should work.

# ? Oct 30, 2008 16:35

Sexxxy Sophitia: Aug 28, 2008; Anime Baby

ShoulderDaemon posted:

%d wants an int parameter. Even if pow returned an int instead of a double, you can't fit the number you want in an int, by definition. Replace %d in this line with %.0f and it should work.

That can't be the only problem because it happens with my char too, which will fit in an int.

Okay, here's the sections I need help with

code:

#include <stdio.h>
#include <math.h>

int main(){

int x;
char y;
short z;
long w;

/*Crap that doesn't apply goes here*/

printf("INT\n");
printf("An int value stores %d byte(s)\n",sizeof(x));
printf("Which means it can store %d bits.\n",sizeof(x)*8);
printf("That means it can store %d values.\n",pow(2,(sizeof(x)*8)));

printf("CHAR\n");
printf("A char value stores %d byte(s)\n",sizeof(y));
printf("Which means it can store %d bits.\n",sizeof(y)*8);
printf("That means it can store %d values.\n",pow(2,(sizeof(y)*8)));

printf("SHORT\n");
printf("A short value stores %d byte(s)\n",sizeof(z));
printf("Which means it can store %d bits.\n",sizeof(z)*8);
printf("That means it can store %d values.\n",pow(2,(sizeof(z)*8)));

printf("LONG\n");
printf("A long value stores %d byte(s)\n",sizeof(w));
printf("Which means it can store %d bits.\n",sizeof(w)*8);
printf("That means it can store %d values.\n",(pow(2,(sizeof(w)*8))));

Here's what it's returning:

code:

INT
An int value stores 4 byte(s)
Which means it can store 32 bits.
That means it can store 1106247680 values.
CHAR
A char value stores 1 byte(s)
Which means it can store 8 bits.
That means it can store 1081081856 values.
SHORT
A short value stores 2 byte(s)
Which means it can store 16 bits.
That means it can store 1089470464 values.
LONG
A long value stores 4 byte(s)
Which means it can store 32 bits.
That means it can store 1106247680 values.

# ? Oct 30, 2008 16:39

Mustach: Mar 2, 2003; In this long line, there's been some real strange genes. You've got 'em all, with some extras thrown in.

pow() returns a double. Using %d to print a double will give you incorrect output. That is the only problem.

# ? Oct 30, 2008 16:57

Rocko Bonaparte: Mar 12, 2002; Every day is Friday!

csammis, I started moving over to jface. I don't see an explicit listener for doing sorting, so I don't think there's a spot where I can disable table refresh when moving the rows around. Still, with about 500 entries it's taking about two seconds to sort by ~4-letter strings (stock symbols). Doesn't that seem like a long time?

I could dismiss it and eat the sort hit, but I plan to have many more entries in that table by the time I'm done, which will put an annoying sort penalty on me.

# ? Oct 30, 2008 17:20

Sexxxy Sophitia: Aug 28, 2008; Anime Baby

Okay so that worked, now how do i get this to work?

code:

long w, xx, xy, xz, xw;
xx = pow(2,(sizeof(x)*8));
xy = pow(2,(sizeof(y)*8));
xz = pow(2,(sizeof(z)*8));
xw = pow(2,(sizeof(w)*8));


printf("To find the range of an unsigned int\nYou would take the number of values it can store %.0f\nAnd subtract one to get %.0f.\n",xx,xx-1);
frintf("To find the range of a signed int\nYou would again start with the number of values it can store %.0f.\nThis time you divide by two and get %0f.\nPut a negative sign in front of that number and you have the lowest value -%.0f.\nSubtract one from that value and you have the highest value %.0f.\n\n",xx,xx/2,xx/2,xx/2-1);

It returns this

p66.c: In function `main':
p66.c:10: warning: overflow in implicit constant conversion
p66.c:13: warning: overflow in implicit constant conversion
Undefined first referenced
symbol in file
frintf /var/tmp//ccqdI89E.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status

EDIT: So this post is obnoxiously wide is ther a better way to post that?

Sexxxy Sophitia fucked around with this message at 17:45 on Oct 30, 2008

# ? Oct 30, 2008 17:28

Mustach: Mar 2, 2003; In this long line, there's been some real strange genes. You've got 'em all, with some extras thrown in.

It's the same problem: pow() returns a double, but none of those variables that you're assigning the results to are doubles.

# ? Oct 30, 2008 17:37

ShoulderDaemon: Oct 9, 2003; support goon fund; Taco Defender

You also now have a typo: frintf instead of printf.

# ? Oct 30, 2008 18:03

Sexxxy Sophitia: Aug 28, 2008; Anime Baby

Okay I got it, thanks guys.

Is there a way to write a program that will finger just my classmates?

if I have a users file that has the usernames of the people in my class

finger
the if any of the usernames I have are in the first field, print the first and second field of that line in the finger, else printf "No one is online"

# ? Oct 30, 2008 18:29

yippee cahier: Mar 28, 2005

Does anyone have any DNG experience? I have a raw bayer pattern and am trying to wrap it in a very basic DNG file so I can demosaic it later. Using libtiff I have managed to make a TIFF file containing the bayer pattern. What are the bare minimum TIFF tags I need to add to this file to so it can be identified as a DNG?

# ? Oct 30, 2008 21:38

csammis: Aug 26, 2003; Mental Institution

sund posted:

Does anyone have any DNG experience? I have a raw bayer pattern and am trying to wrap it in a very basic DNG file so I can demosaic it later. Using libtiff I have managed to make a TIFF file containing the bayer pattern. What are the bare minimum TIFF tags I need to add to this file to so it can be identified as a DNG?

I assume you're talking about Digital Negative format here? Maybe the Adobe file specification will tell you what you need to know.

# ? Oct 30, 2008 21:48

fankey: Aug 31, 2001

sund posted:

Does anyone have any DNG experience? I have a raw bayer pattern and am trying to wrap it in a very basic DNG file so I can demosaic it later. Using libtiff I have managed to make a TIFF file containing the bayer pattern. What are the bare minimum TIFF tags I need to add to this file to so it can be identified as a DNG?

dcraw might be of some use. He has some sample code on that page to write out DNG files.

# ? Oct 30, 2008 22:13

ten_twentyfour: Jan 24, 2008

nvm.

ten_twentyfour fucked around with this message at 23:03 on Oct 30, 2008

# ? Oct 30, 2008 22:27

squiffy: Aug 3, 2007; Rebus: TTT

I'm writing a small plugin for Audacity in Nyquist. Nyquist uses LISP.
The plugin should delete regular intervals from audio specified by the user.
I'm having awful trouble getting the correct amount of audio to be deleted and the loops just don't seem to work at all.

code:

;nyquist plug-in
;version 1
;type process
;name "Delete Regular Intervals..."
;action "Deleting..."
;control interval "Every" real "s" 0.1 0.001 1.0
;control delAmount "Delete this amount" real "s" 0.1 0.001 1.0

(defun delInterval (j d r) ; delInterval(interval, deleteAmount, sound source)
	(setf s-length (* (get-duration 1)))
	(setf maxAmount (truncate (/ s-length interval)))
	(setf chan0 (const 0 0)) ;init chan0
	(dotimes (n (- maxAmount 1) chan0) 
		(setf chan (extract-abs (+ (* n j) d) (* j (+ n 1)) r))
		(setf chan0 (seq chan0 chan))
	)
)

(if (arrayp s) ;Splits stereo source into l and r channels
	(vector 
	(delInterval interval delAmount (aref s 0))
	(delInterval interval delAmount (aref s 1)))
    (delInterval interval delAmount s) ;Mono source
)

Essentially the behaviour of the plugin is to extract slices of the audio at regular intervals and sequentially place them in a new variable.
This is as far as I have got over the past few days and it's driving me insane. I think it may be a problem with the extract function, or perhaps it's a very simple error in the logic of my implementation.
I don't hold out any hope for anyone to know LISP or even Nyquist, but thanks anyway!

# ? Oct 31, 2008 00:54

Chuu: Sep 11, 2004; Grimey Drawer

My brain is completely melted after working 60 hours on some stupid thread code and I can't write a simple algorithm. Halp.

An application represent numbers as two integers. One is the value, the other is the decimal location.

Examples:

2.21 : VALUE(221) LOC(2)
504 : VALUE(504) LOC(0)
3.442 : VALUE(3442) LOC (3)

I need a good way to take a double and convert it into two a value/loc combo. Originally I just did this:

code:

(c++)

double price = thread.getValue();
int decloc = 0;
while( price - ((int)price) != 0)
{
	price*=10;
	decloc++;
}

This code does not work for because of double's native representation that doesn't correspond well to Decimal, which are easier to gut check then explain (3.43 -> 3.43000000000001 -> 3430000000000001 * 10 -> +inf).

Valid range of double values is from 0000.1 to 99999.

I'm assuming just adding an /epsilon value and checking the remainder against it is all I need to fix this, but my brain is so fried I can't formulate it.

Any help?

Chuu fucked around with this message at 04:49 on Oct 31, 2008

# ? Oct 31, 2008 04:09

Marx Headroom: May 10, 2007; AT LAST! A show with nonono ~~commercials~~!; Fallen Rib

I hit a roadblock on my very first Haskell program:

http://www.quickfilepost.com/download.do?get=1f573e1d8ff015815ea5022923b120d3

code:

Prelude> :load scan.hs
[1 of 1] Compiling Main             ( scan.hs, interpreted )

scan.hs:11:150:
    lexical error in string/character literal at character '\n'
Failed, modules loaded: none.

I'm using OSX's TextEdit because I'm lazy, does the UTF-8 encoding have anything to do with this? How can I fix it?

# ? Oct 31, 2008 21:27

ShoulderDaemon: Oct 9, 2003; support goon fund; Taco Defender

Mr. Jive posted:

I hit a roadblock on my very first Haskell program:

You're missing a quote on line 11, right before FOR.

# ? Oct 31, 2008 21:35

Marx Headroom: May 10, 2007; AT LAST! A show with nonono ~~commercials~~!; Fallen Rib

Thanks. This is nerve-wracking.

# ? Oct 31, 2008 21:37

Scaevolus: Apr 16, 2007

Chuu posted:

This code does not work for because of double's native representation that doesn't correspond well to Decimal, which are easier to gut check then explain (3.43 -> 3.43000000000001 -> 3430000000000001 * 10 -> +inf).

Valid range of double values is from 0000.1 to 99999.

I'm assuming just adding an /epsilon value and checking the remainder against it is all I need to fix this, but my brain is so fried I can't formulate it.

Any help?

I would do something like sprintf(buff, "%.8f", float) and parse the resulting string instead of manually converting a float.

# ? Oct 31, 2008 23:08

Pupienus: Jul 21, 2003

I've got a problem with Visual Studio 2008. Since it seemed more of a compiler issue than a language issue, I'm trying it here first. It's in C++, and I've got some files from the professor I need to use, but it's throwing a fit at things like this:

code:

#ifndef WIN32
  gzFile gzfp;
#endif

It doesn't seem to be excluding anything in the #ifndef or #ifdef blocks, so when it sees anything related to non-windows compatibility, it shits a brick. Am I gonna have to strip all these out one at a time or is there a way to make them work properly?

# ? Nov 1, 2008 01:09

Mustach: Mar 2, 2003; In this long line, there's been some real strange genes. You've got 'em all, with some extras thrown in.

Go to Project >> Whatever Your Project is Called Properties >> Configuration Properties >> C/C++ >> Preprocessor, make sure WIN32 is part of the Preprocessor Definitions.

# ? Nov 1, 2008 02:39

Pupienus: Jul 21, 2003

Thanks, that's what I needed. I managed a workaround until this point by getting the library it was looking for, but this works better.

# ? Nov 1, 2008 02:56

csammis: Aug 26, 2003; Mental Institution

Mustach posted:

Go to Project >> Whatever Your Project is Called Properties >> Configuration Properties >> C/C++ >> Preprocessor, make sure WIN32 is part of the Preprocessor Definitions.

WIN32 is also defined when you include <windows.h>

# ? Nov 1, 2008 03:49

csammis: Aug 26, 2003; Mental Institution

# ? Nov 1, 2008 03:50

Chuu: Sep 11, 2004; Grimey Drawer

Unless I'm missing something, CppUnit doesn't really have a way to directly access the private internals of a class like JUnit does.

1. Am I wrong? If so, what's the syntax?

2. Is there a clean way to work around this, without resorting to hacks like #ifdef x #define private public, making everything virtual and subclass, etc? Can I use 'friend' for this somehow, without really making the tested class aware of the unit test class?

Chuu fucked around with this message at 06:43 on Nov 1, 2008

# ? Nov 1, 2008 06:38

microwave casserole: Jul 5, 2005; my god, what are you doing

edit: Woops, I just found out that there was a specific PHP thread for this kind of question.

microwave casserole fucked around with this message at 20:40 on Nov 1, 2008

# ? Nov 1, 2008 20:35

Nahrix: Mar 17, 2004; Can't afford to eat out

(Language: C) Is there a simple way to read a char array[x] -> array[last_element], where y > 0?

I just want to read a string, starting from a given index. (eg. read "ello" from "hello"). I don't want to make a for loop for this.

# ? Nov 4, 2008 21:56

6174: Dec 4, 2004

Nahrix posted:

(Language: C) Is there a simple way to read a char array[x] -> array[last_element], where y > 0?

What is y?

Nahrix posted:

I just want to read a string, starting from a given index. (eg. read "ello" from "hello"). I don't want to make a for loop for this.

Why do you think a for loop is somehow inappropriate?

Also, there is a C/C++ thread for questions like this.

# ? Nov 4, 2008 22:08

ShoulderDaemon: Oct 9, 2003; support goon fund; Taco Defender

Nahrix posted:

(Language: C) Is there a simple way to read a char array[x] -> array[last_element], where y > 0?

I just want to read a string, starting from a given index. (eg. read "ello" from "hello"). I don't want to make a for loop for this.

If you have char buffer[] = "Hello, World!" and you want a char * to just the second word, you can use char *world = &buffer[7] or, more directly, char *world = buffer + 7.

# ? Nov 4, 2008 22:37

rjmccall: Sep 7, 2007; no worries friend; Fun Shoe

ShoulderDaemon posted:

If you have char buffer[] = "Hello, World!" and you want a char * to just the second word, you can use char *world = &buffer[7] or, more directly, char *world = buffer + 7.

This, and if you need a copy for some reason you can use strcpy (or memcpy and an explicit terminator if it's a non-terminal substring).

# ? Nov 4, 2008 22:46

Nubile Cactus: Aug 1, 2004; I am a cactus. :)

Anyone have a quick data structure reference? I need to brush up on a few structures and the big O complexity before a technical interview.

# ? Nov 6, 2008 03:38

sd6: Jan 14, 2008; This has all been posted before, and it will all be posted again

Does anyone know of a good intro tutorial online to writing programs that modify behavior of other programs? I'm talking about things like the Steam achievement manager or D2 character editors, but it wouldn't have to be that complex or even have anything to do with games. I just want to understand how people write programs that are dependent on or change the behavior of other existing programs.

# ? Nov 6, 2008 06:30

ante: Apr 9, 2005; SUNSHINE AND RAINBOWS

Queef Olbermann posted:

Does anyone know of a good intro tutorial online to writing programs that modify behavior of other programs? I'm talking about things like the Steam achievement manager or D2 character editors, but it wouldn't have to be that complex or even have anything to do with games. I just want to understand how people write programs that are dependent on or change the behavior of other existing programs.

This is kinda vague, but there are a few different ways, depending upon what you're trying to do.

Google "dll injection", "hooks", and the FindWindow function.

Dll injection will let you inject code into a program so that it'll run whatever code you want.

Hooks allow you to capture the event handlers of other programs. I've never really used them, so I can't help you there.

FindWindow is just a function that'll return the handle of a window. Look in that entire section of Microsoft's documentation. You can use find child objects(such as buttons) on the form and use SendMessage to chenge text, press buttons, etc.
That's probably the easiest of the three.

# ? Nov 6, 2008 08:44

baquerd: Jul 2, 2007; by FactsAreUseless

Anyone know of an open-source cron replacement with a web based GUI suitable for enterprise development? I'm just being lazy and want to extend someone's else's fleshed out framework. PHP, Java, whatever.

# ? Nov 6, 2008 11:34

dagard: Mar 31, 2005

quadreb posted:

Anyone know of an open-source cron replacement with a web based GUI suitable for enterprise development? I'm just being lazy and want to extend someone's else's fleshed out framework. PHP, Java, whatever.

Webmin has a cron interface, as I recall. I've used it before to let developers see production logfiles without giving them actual logins on the servers.

# ? Nov 6, 2008 15:03

baquerd: Jul 2, 2007; by FactsAreUseless

dagard posted:

Webmin has a cron interface, as I recall. I've used it before to let developers see production logfiles without giving them actual logins on the servers.

Nifty looking package, but I'm looking for something that is a replacement for, not interacts with. But thank you anyway! Think it's just time to start planning out the structure

# ? Nov 6, 2008 15:09

sd6: Jan 14, 2008; This has all been posted before, and it will all be posted again

ante posted:

This is kinda vague, but there are a few different ways, depending upon what you're trying to do.

Alright I'll give those a look, thanks!

# ? Nov 6, 2008 16:41

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# ? May 14, 2024 11:39

Runaway Five: Dec 31, 2007; I hate gays almost as much as I hate good posting. Also, God is good. Amen

I have a question and a half.

When you use the STL Standard Map, it is implemented as a "Binary Tree" and therefore runs in O(lg) time.

Is there a STL form of a hash table, one that would work in O(k) time and preferably have a subscript operator? Thanks in advance.

Also, is there such a thing as a hash map?

# ? Nov 6, 2008 19:05

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Ask General Programming Questions Not Worth Their Own Thread

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