Newb Question Character Counting

Wilder · 06-21-2008, 11:10 PM

First of all as the title suggest I am a newb. I pretty much just started to try and teach myself C, and I would like you to help me if possible.

I am trying to create a small program that counts characters. I am following along in a book and I entered the code exactly as it says, but it doesn't work like it should (it does compile though). I'll post the code below.

Code:

#define EOF -1

main ()
{
	long nc;
	
	nc = 0;
	while (getchar() != EOF)
		++nc;
	printf("%1d\n", nc);
}

Like I said it compiles fine and that is what the book says works. I think the problem is that its getting stuck in the while statement and thus will never actually get to the printf function. I tried myself before posting to try to arrange it in a way that would work, but couldn't seem to figure it out. Like I said I'm a newb to C (along with programming in general) so any help is greatly appreciated.

Cactus_Hugger · 06-21-2008, 11:48 PM

You need to send a EOF. Either pipe a file in through stdin, like:

Code:

cat somefile.txt | yourprogram
Or, if you're on Windows
type somefile.txt | yourprogram

Or, send an EOF. I believe it's Ctrl+Z, but I could be wrong.

Edit: Also, main() returns an int! Make it such!

Code:

int main()
{
    // ... code ...
    return 0;  // or some nonzero number if errors occur.
}

Wilder · 06-21-2008, 11:55 PM

Thanks, pretty sure I understand now.

Elysia · 06-22-2008, 04:57 AM

http://cpwiki.sourceforge.net/Implicit_main

foxman · 06-22-2008, 09:50 AM

Quote:

Originally Posted by Cactus_Hugger

Or, send an EOF. I believe it's Ctrl+Z, but I could be wrong.

Note that on Unix and Unix-like system, the right combination of key is Ctrl+D, where in Windows, it's Ctrl+Z.

Oh and Wilder, don't forget to include stdio.h in your source file (#include <stdio.h>) and remove that line where you define EOF.

Wilder · 06-22-2008, 04:12 PM

I changed the code around a little bit so it is now:

Code:

#include <stdio.h>

main()
{
	long nc;
	
	nc = 0;
	while (getchar() != EOF)
		++nc;
	printf("%1d\n", nc);
	while (1 != 0) // Only here so that the DOS window doesn't close automatically 
		;      // so I can view the result. 
}

After I finish typing the characters that I want counted I have to push CTRL+Z then enter and it will display the correct result. My next question is there anyway I can arrange it so that after I push enter it will count the characters I typed so that I don't need to do CTRL+Z? Like I said before I'm new to C, but I'm guessing where it says while (getchar() != EOF) I would change EOF to whatever the value for enter would be?

Elysia · 06-22-2008, 09:46 PM

http://cpwiki.sourceforge.net/Implicit_main
Just use fgets instead.

dwks · 06-22-2008, 09:52 PM

Quote:

My next question is there anyway I can arrange it so that after I push enter it will count the characters I typed so that I don't need to do CTRL+Z? Like I said before I'm new to C, but I'm guessing where it says while (getchar() != EOF) I would change EOF to whatever the value for enter would be?

Bingo! And that is: '\n'. With the single quotes and all.

Or you could use a function that does it all for you, like fgets(), as Elysia suggested. Personally, I wouldn't, though; you're just counting characters, after all, so reading one character at a time makes more sense than reading a whole line all in one go . . . .

Also: the "1" in %1d is entirely optional. This works just fine.

Code:

printf("%d\n", nc);

Code:

	while (1 != 0) // Only here so that the DOS window doesn't close automatically 
		;      // so I can view the result.

That works, it's true. (Though there are shorter ways, most notably while(1) and for(;;).)

However, it uses 100% of your processor, so it's not ideal. You could put another getchar() in there to wait for a key to be pressed, but I don't think that would work after you type EOF, so only try this once you have the '\n'/fgets() thing working.

Wilder · 06-22-2008, 11:07 PM

Thanks for the help, I really appreciate it. The program now works just like I want it to. Final code is:

Code:

// Counts the number of characters in the input
#include <stdio.h>

int main()
{
	long nc;
	
	nc = 0;
	printf("Please type a phrase then press ENTER to see how many charcters it has.\n\nInput: ");
	while (getchar() != '\n')
		++nc;
	printf("\nThe input has %d characters.\n\nPress ENTER to exit", nc);
	getchar(); // Used to prevent DOS window from closing automatically
	return 0;
}

The getchar() at the end now works as a way to stop DOS window from exiting automatically now that I'm not using the EOF which works much better. Once again thanks for all the help.

Elysia · 06-22-2008, 11:08 PM

Do you even read links that are posted?

dwks · 06-22-2008, 11:15 PM

Well, because it was just a bare link with no explanation, you could think by accident that it was related to fgets() . . . .

But still, Elysia is right, of course. You should use "int main()" and add a "return 0;" statement to the end of main(). The way you have it is relying on the implicit int rule, which is deprecated. But I'm sure I'm just repeating Elysia's link, which I urge you to read.

http://cpwiki.sourceforge.net/Implicit_main

[edit] I just know it's going to start a "main" debate, but int main() is actually a better idea than int main(void), because main() is going to be passed some parameters whether you like it or not, and stating int main(void) tells the compiler that no parameters will be passed, while int main() says that anything could be passed. At least, this is what someone said in the last debate. (Was it brewbuck?) I don't buy into it, myself . . . . [/edit]

Elysia · 06-22-2008, 11:28 PM

Quote:

Originally Posted by dwks

[edit] I just know it's going to start a "main" debate, but int main() is actually a better idea than int main(void), because main() is going to be passed some parameters whether you like it or not, and stating int main(void) tells the compiler that no parameters will be passed, while int main() says that anything could be passed. At least, this is what someone said in the last debate. (Was it brewbuck?) I don't buy into it, myself . . . . [/edit]

I don't really have many arguments there. Either one is acceptable to me.
Just not implicit main.

Wilder · 06-22-2008, 11:31 PM

Ok i edited it a bit. Should be all right now?

dwks · 06-22-2008, 11:37 PM

Perfect! Well, just about . . .

%d is for ints; nc is a long. nc should either be an int, or you should use the format specifier for longs: %ld.

Code:

printf("%ld\n", nc);

There's only one other thing with it that I can see which might cause some trouble: the printf() statement at the end. It doesn't end with a newline.

You see, consoles are typically line-buffered; that is, they might only display what you've printed to them when you print a newline. So, in some cases, your message might not be printed.

You could fix this by ending the printf with a newline, which I would recommend.

You could also use fflush(stdout) to force the output to be written to the screen, but that's probably just too complicated for something that probably will never happen.

[edit] This "buffer" thing needs elaboration.

With files and other sources of input and output, it's generally inefficient to read just one character at a time. For this reason, the operating system often reads or writes data in largish chunks. When you write one character to a file, it's stored in a buffer instead of being written immediately. When this buffer gets full, then, and only then, is the data written to the file. It's more efficient this way.

Unfortunately, this can cause some trouble for us programmers. For example, if you terminate a program that is writing to a file, the latest changes might not have been written to the file. In your case, data you write to the screen might not be visible unless you print a newline. But buffering is still a good thing. Your computer would be very slow without it.

Fortunately, you can force whatever's in the buffer to be written to the file or to the screen immediately. Which I indicated, with fflush(). Since the screen is line-buffered, you can also just print a newline to force the buffer to be flushed. [/edit]

06-21-2008, 11:10 PM	#1
Wilder Registered User Join Date: Jun 2008 Posts: 5	Newb Question Character Counting First of all as the title suggest I am a newb. I pretty much just started to try and teach myself C, and I would like you to help me if possible. I am trying to create a small program that counts characters. I am following along in a book and I entered the code exactly as it says, but it doesn't work like it should (it does compile though). I'll post the code below. Code: #define EOF -1 main () { long nc; nc = 0; while (getchar() != EOF) ++nc; printf("%1d\n", nc); } Like I said it compiles fine and that is what the book says works. I think the problem is that its getting stuck in the while statement and thus will never actually get to the printf function. I tried myself before posting to try to arrange it in a way that would work, but couldn't seem to figure it out. Like I said I'm a newb to C (along with programming in general) so any help is greatly appreciated.
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06-21-2008, 11:48 PM	#2
Cactus_Hugger int x = ((int ) NULL); Join Date: Jul 2003 Location: Banks of the River Styx Posts: 891	You need to send a EOF. Either pipe a file in through stdin, like: Code: cat somefile.txt \| yourprogram Or, if you're on Windows type somefile.txt \| yourprogram Or, send an EOF. I believe it's Ctrl+Z, but I could be wrong. Edit: Also, main() returns an int! Make it such! Code: int main() { // ... code ... return 0; // or some nonzero number if errors occur. } __________________ long time; /* know C? */ Unprecedented performance: Nothing ever ran this slow before. Any sufficiently advanced bug is indistinguishable from a feature. Real Programmers confuse Halloween and Christmas, because dec 25 == oct 31. The best way to accelerate an IBM is at 9.8 m/s/s. recursion (re - cur' - zhun) n. 1. (see recursion)
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06-21-2008, 11:55 PM	#3
Wilder Registered User Join Date: Jun 2008 Posts: 5	Thanks, pretty sure I understand now.
Wilder is offline

06-22-2008, 04:12 PM	#6
Wilder Registered User Join Date: Jun 2008 Posts: 5	I changed the code around a little bit so it is now: Code: #include <stdio.h> main() { long nc; nc = 0; while (getchar() != EOF) ++nc; printf("%1d\n", nc); while (1 != 0) // Only here so that the DOS window doesn't close automatically ; // so I can view the result. } After I finish typing the characters that I want counted I have to push CTRL+Z then enter and it will display the correct result. My next question is there anyway I can arrange it so that after I push enter it will count the characters I typed so that I don't need to do CTRL+Z? Like I said before I'm new to C, but I'm guessing where it says while (getchar() != EOF) I would change EOF to whatever the value for enter would be?
Wilder is offline

06-22-2008, 11:07 PM	#9
Wilder Registered User Join Date: Jun 2008 Posts: 5	Thanks for the help, I really appreciate it. The program now works just like I want it to. Final code is: Code: // Counts the number of characters in the input #include <stdio.h> int main() { long nc; nc = 0; printf("Please type a phrase then press ENTER to see how many charcters it has.\n\nInput: "); while (getchar() != '\n') ++nc; printf("\nThe input has %d characters.\n\nPress ENTER to exit", nc); getchar(); // Used to prevent DOS window from closing automatically return 0; } The getchar() at the end now works as a way to stop DOS window from exiting automatically now that I'm not using the EOF which works much better. Once again thanks for all the help. Last edited by Wilder; 06-22-2008 at 11:33 PM.
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06-22-2008, 11:15 PM	#11
dwks Frequently Quite Prolix Join Date: Apr 2005 Location: Canada Posts: 7,629	Well, because it was just a bare link with no explanation, you could think by accident that it was related to fgets() . . . . But still, Elysia is right, of course. You should use "int main()" and add a "return 0;" statement to the end of main(). The way you have it is relying on the implicit int rule, which is deprecated. But I'm sure I'm just repeating Elysia's link, which I urge you to read. http://cpwiki.sourceforge.net/Implicit_main [edit] I just know it's going to start a "main" debate, but int main() is actually a better idea than int main(void), because main() is going to be passed some parameters whether you like it or not, and stating int main(void) tells the compiler that no parameters will be passed, while int main() says that anything could be passed. At least, this is what someone said in the last debate. (Was it brewbuck?) I don't buy into it, myself . . . . [/edit] __________________ dwk Seek and ye shall find. quaere et invenies. "Simplicity does not precede complexity, but follows it." -- Alan Perlis "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra "The only real mistake is the one from which we learn nothing." -- John Powell Other boards: DaniWeb, TPS Unofficial Wiki FAQ: cpwiki.sf.net My website: http://dwks.theprogrammingsite.com/ Projects: codeform, xuni, atlantis, etc. New project: nort Last edited by dwks; 06-22-2008 at 11:17 PM.
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06-22-2008, 11:31 PM	#13
Wilder Registered User Join Date: Jun 2008 Posts: 5	Ok i edited it a bit. Should be all right now?
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06-22-2008, 11:37 PM	#14
dwks Frequently Quite Prolix Join Date: Apr 2005 Location: Canada Posts: 7,629	Perfect! Well, just about . . . %d is for ints; nc is a long. nc should either be an int, or you should use the format specifier for longs: %ld. Code: printf("%ld\n", nc); There's only one other thing with it that I can see which might cause some trouble: the printf() statement at the end. It doesn't end with a newline. You see, consoles are typically line-buffered; that is, they might only display what you've printed to them when you print a newline. So, in some cases, your message might not be printed. You could fix this by ending the printf with a newline, which I would recommend. You could also use fflush(stdout) to force the output to be written to the screen, but that's probably just too complicated for something that probably will never happen. [edit] This "buffer" thing needs elaboration. With files and other sources of input and output, it's generally inefficient to read just one character at a time. For this reason, the operating system often reads or writes data in largish chunks. When you write one character to a file, it's stored in a buffer instead of being written immediately. When this buffer gets full, then, and only then, is the data written to the file. It's more efficient this way. Unfortunately, this can cause some trouble for us programmers. For example, if you terminate a program that is writing to a file, the latest changes might not have been written to the file. In your case, data you write to the screen might not be visible unless you print a newline. But buffering is still a good thing. Your computer would be very slow without it. Fortunately, you can force whatever's in the buffer to be written to the file or to the screen immediately. Which I indicated, with fflush(). Since the screen is line-buffered, you can also just print a newline to force the buffer to be flushed. [/edit] __________________ dwk Seek and ye shall find. quaere et invenies. "Simplicity does not precede complexity, but follows it." -- Alan Perlis "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra "The only real mistake is the one from which we learn nothing." -- John Powell Other boards: DaniWeb, TPS Unofficial Wiki FAQ: cpwiki.sf.net My website: http://dwks.theprogrammingsite.com/ Projects: codeform, xuni, atlantis, etc. New project: nort Last edited by dwks; 06-22-2008 at 11:44 PM.
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