Character Counting Program

[DemosthenesB]

I just started to learn C with the book "The C Programming Language." I am only in the first chapter and am already experiencing problems

There is an section on Character Input and Output. The first example is a "Character Counting" program. The script is a s follows:

#include <stdio.h>

/*count chars in input, 1st version*/

main ()
{
	long nc;

	nc = 0;
	while (getchar() != EOF)
		++nc;
	printf("%ld\n", nc);
}

What am I supposed to get when I run the program? So far all I can do it type and the text will show, nothing else.

P.S. Just to let you know I am using Slackware Linux, maybe that has something to do with it...

[sde]

i think the program is executing and exiting so quick that you can't see the output .. try this:

#include <stdio.h>

/*count chars in input, 1st version*/

main ()
{
	long nc;

	nc = 0;
	while (getchar() != EOF)
		++nc;
	printf("%ld\n", nc);

	printf("\n\n Press any key to exit.");
	
	getchar(); 
}

i'm sorta a n00b myself, but i think this will do it.

[DemosthenesB]

Thank you for your help sde, but it still does not work, or at least doesn't output something. Maybe you could explain what it actually does(what the output is supposed to look like), or if it is even suposed to have an output.

Thank you very much.

[abc123]

the program does exactly what is intended, and upon you ending input (EOF) it will display the number of characters you pressed..

EOF is probably crtl-Z, so type your characters then press crtl-z and it will display no. of chars and exit.

[JJoSA]

Yup, it's waiting for the EOF character from your input. If you're running on a Unix box, it's CTRL-D

[peted]

yep, JJoSA has it. The program you are compiling reads each character you enter from the keyboard in a loop until it reaches a special character called an End Of File (EOF) character. Your standard keyboard doesn't include this special character so you have to send it using a control sequence. Under linux the control sequence for an EOF is to hold the control key and press 'd' (Commonly presented as Ctrl-D).

So, run the program, type your message that you want character counted and when you've finished press Ctrl-D.

The control sequence that abc123 stated (Ctrl-Z) suspends a process (puts it in the background). To explain this i'd have to go into kernel process schedulers and i'll be here for hours. The best book in my opinion to describe kernel processes is Operating Systems by Andrew Tanenbaum.

Hope this helps.

[joe_bruin]

Originally posted by peted
The control sequence that abc123 stated (Ctrl-Z) suspends a process (puts it in the background).

you're both right. in dos/windows ctrl-z is the EOF combo.
in unix, like you said, it is ctrl-d, and ctrl-z suspends a process.

[DemosthenesB]

YAY!~ Thank you guys SO much . I tried it with ctl+D and it works, thanks again.

[TheDreamless]

Something we did in my intro C class that helped me to understand the way input from files and out to files worked was take a text file in unix and count all the lines, characters (dont include spaces tabs or end lines), and remove the vowels and then print them into an output file. Once you can do this you will pretty much have the hang of these types of programs. I know that your example code was reading from stdin but it seems the book is working towards redirected in and out since it used EOF.