Please tell me if I've written this correctly

[Sathyaish]

Hi friends,

I am beginning to practice C from K&R. Although I am only familiar with the language, this time I want to invest time learning it
thoroughly. I've written this practice excercise program to replace more than a single blank in an input with only a single blank in the
output. Here's the code.

#include <stdio.h>

/*A program that displays keyboard input to the monitor, but trimming
more than a single space to a single space I've not replaced tabs with single 
spaces yet*/

#define SPACE 1

void main()
{

 int c, state;
 c=0;
 state=SPACE;
 while ((c=getchar()) != EOF)
 {
  if (!(state && (c==' '))) putchar(c);

  if (c==' ')
  {
   state=SPACE;
  }
  else
  {
   state= !SPACE;
  } 
 }
}

Although I've tested it four to five times, I don't know if I can be sure as to whether it is right, since I've made guesses about the
BITWISE operators such as NOT to be the same as the logical NOT ! and the BITWISE AND to be the same as the LOGICAL AND (&&). Also, on purpose, I have not yet detected tabbed spaces.

Could you gurus please tell me if I've written this program correctly?

[Paul McKenzie]

Originally posted by Sathyaish
Hi friends,

I am beginning to practice C from K&R.

What books do you have to use as a reference?

Here's the code.

//...
void main()

That's int main(), not void main()

Although I've tested it four to five times, I don't know if I can be sure as to whether it is right, since I've made guesses about the
BITWISE operators such as NOT to be the same as the logical NOT ! and the BITWISE AND to be the same as the LOGICAL AND (&&)

Again, a good C book will point out the differences. The bitwise AND/OR is not the same as the logical AND/OR.

Basically, what you want to do is to learn the language properly, and not rely on guesses. Also, usage of a debugger is helpful in finding out what your program is doing.

Regards,

Paul McKenzie

[Sathyaish]

Besides K&R, I have two three books on C, one Balaguru swamy, and another by two Indian authors, one by Yashwant Karnitkar and one by Johnathan Morrison (that's for C++ actually). I also have course books from NIIT, and have read a few tutorials. Besides, I have worked extensively on Win32 SDK. And I started out learning C++ as my first language so I am kinda familiar with it.

That's int main(), not void main()

I am aware of that, but I didn't want to return a value from main so I, on purpose, cast the return type as void.

[Sathyaish]

And I also realize I could have written

	/********************************************************************
		if (c==' ')
		{
			state=SPACE;
		}
		else
		{
			state= !SPACE;
		}
		*/
		//I could better write the above if construct as
		state = (c==' ');
		//**********************************************************************

I'd be grateful for help. The debugger, I did use but since the functions getchar and putchar are buffered, as I've been explained, I found it difficult to use the debugger. I am told many C/C++ programmers find the Visual C++ debugger a nightmare to dream.

[nsh123]

Originally posted by Sathyaish
Besides K&R, I have two three books on C, one Balaguru swamy, and another by two Indian authors, one by Yashwant Karnitkar and one by Johnathan Morrison (that's for C++ actually). I also have course books from NIIT, and have read a few tutorials. Besides, I have worked extensively on Win32 SDK. And I started out learning C++ as my first language so I am kinda familiar with it.



I am aware of that, but I didn't want to return a value from main so I, on purpose, cast the return type as void.

C++ int main() is ok. As we are dicussing C, it is strictly int main(void).

regards

Mike

[gstercken]

What I don't understand: You say you already know C++, and you're now learning C. But C is a subset of C++, so all you have to learn are the limitations of C as compared to C++. Basically, if you know C++, you know C as well. Of course you will have to learn about the functions of the C standard library. However, the things you are asking here about bitwise or logical operators are exactly the same in C++ as they are in C.

[Paul McKenzie]

Originally posted by Sathyaish
I am aware of that, but I didn't want to return a value from main so I, on purpose, cast the return type as void.

No. The return type for main() has always been int, even for ANSI C programs.

The main() function is special in that you do not need to specify a return value. If you don't return a value, by rule, the return is implied to be a 0. You don't change the prototype for main() just because you're not returning a value.

Regards,

Paul McKenzie