Thread: little help for newb

ive decided to learn c, as a base to learn object c cocoa and java, so i got a copy of K&R and was fine for few pages, wrote a few short things from imagination which worked and i was happy, but then the next example fails to compile, so its not me cause its the example and i just get an error when compiling it.

im using xcode, so there is a chance i could have set that up wrong, but i didnt get any errors till this example.

the example is

Code:

#include <stdio.h> 
#define IN 1 /* inside a word */ 
#define OUT 0 /* outside a word */ 
/* count lines, words, and characters in input */ 
main() 
{ 
	int c, nl, nw, nc, state; 
	state = OUT; 
	nl = nw = nc = 0; 
	while ((c = getchar()) != EOF) { 
	++nc;
		if (c == '\n') 
			++nl; 
		if (c == ' ' || c == '\n' || c = '\t') 
			state = OUT; 
		else if (state == OUT) { 
			state = IN; 
			++nw; 
		} 
	} 
	printf("&#37;d %d %d\n", nl, nw, nc); 
}

and the error is shown by xcode as being "if (c == ' ' || c == '\n' || c = '\t') " in that but it could be the line above.
but either way im stuck cause its the first example in the section so i dont understand the subject enough to even have a clue what im doing wrong.

sorry it such a simple question but i cant find anyone with the same problem on the net.
thanks

Yes, I suppose that you are getting "invalid lvalue in assignment" on line 14. That is because you are trying to assing '\t' into

Code:

c == ' ' || c == '\n' || c

- you are lucky, because if you had done:

Code:

(c == ' ') || (c == '\n') || (c = '\t')

then it would have compiled fine, but you would have wondered why the word count was wrong, when all other values where right...

--
Mats

Originally Posted by jimbojones

ive decided to learn c, as a base to learn object c...

Whoa, wait hang on.
Object C of everything. Is there a specific reason you want to learn objective C? If you want to simply learn object-oriented programming, then C++ is the logical step.
And if you want to learn object-oriented programming through C++, then you can skip C altogether.

So, why did you want to learn Objective C again?

Code:

#include <stdio.h> 
#define IN 1 /* inside a word */ 
#define OUT 0 /* outside a word */ 
/* count lines, words, and characters in input */ 
main() 
{ 
	int c, nl, nw, nc, state; 
	state = OUT; 
	nl = nw = nc = 0; 
	while ((c = getchar()) != EOF) { 
	++nc;
		if (c == '\n') 
			++nl; 
		if (c == ' ' || c == '\n' || c == '\t') 
			state = OUT; 
		else if (state == OUT) { 
			state = IN; 
			++nw; 
		} 
	} 
	printf("&#37;d %d %d\n", nl, nw, nc); 
}

Use code tags.
See missing = I added in red. You used assignment, not comparison.

Also, don't use implicit main: http://cpwiki.sourceforge.net/Implicit_main
Bad book.

It's a bad book because it also uses implicit main, which is typically frowned upon today and removed altogether in newer C standards.
The missing "=" was probably a typo.
And you have managed to avoid the why question, regarding objective C...

One of the terms in C is "lvalue", and that is anything that can be on the left side of an assignment.
So, formally, an assignment consists of an lvalue and an rvalue.

Code:

lvalue = rvalue;

So, the lvalue must be something that can be assigned into, such as a simple variable or a pointer dereference.

Something like:

Code:

int a, b;

a + b = 7

obviously doesn't make much sense, and the compiler will say "not an lvalue" because "a + b" is not something that you can assign a value to.

By the way, "l" in lvalue stands for "left", and "r" in rvalue, as you probably could guess is "right".

--
Mats

Originally Posted by whiteflags

I've heard that this is a coincidence, and lvalue actually means location value, given the idea is to store an rvalue somewhere. That should eliminate from the mind things that aren't assignable, such as arrays.

Wikipedia seems to think that L-value is to do with "left" rather than "location", but I suppose it can be seen to mean both things.

http://en.wikipedia.org/wiki/Value_(computer_science)

--
Mats

Originally Posted by rags_to_riches

Jimbo, it seems to me that Elysia is pretty much fully invested in the Microsoft Kool-Aid.

Be that as it may, but nor is everything Microsoft the Source Of All Evil, that some people claim it to be.

QuantumPete

Originally Posted by rags_to_riches

Jimbo, it seems to me that Elysia is pretty much fully invested in the Microsoft Kool-Aid. This seems to have resulted in your specific mention of Cocoa immediately following Objective-C being completely ignored.

There are many languages out there, and I cannot know them all. Cocoa was unknown to me.
Furthermore, Objective C is a pretty bad language if you ask me - it tried to add to C what it severely lacked - objected oriented programming.
However, there is a far more advanced and better language for that which incorporates all C and more which is called C++.
Furthermore, ObjC is not as widely supported as either C or C++ - it is like it is somewhere in between, which is never good.

So then let's change this from languages to another question:
What is it that you wish to do?
Clearly you intend to write some sort of software - where is it targeted? What will they do?
Usually, with the kind of answers, people can suggest you the right tool for the job.