Thread: My doubts

Hi guys,
I am learning C and coming up with a lot of doubts. Kindly spend some time to clear my doubts

Here is my first doubt:

Code:

void main()
{
int i;
for(;scanf("%d",&i);printf("%d",i));
}

How many times will the for loop get executed?

When I ran the program, it didn't even execute once but in the book, the correct answer is given as it will run infinite times.

Kindly throw some light into it.

Mr. grumpy, like I said earlier, I am not an expert in c. I am just a beginner. so, if you can explain a bit more, it would be of great help to me.

Originally Posted by grumpy

You don't need to be an expert, but I am not here to spoonfeed you. I have told you the condition in which the loop will terminate. Find (using google if you like) information on scanf().

I just wanted someone to clear my doubt. I didn't invite you to this thread and asked you to spoonfeed me. If you do not know the answer, why do you post the reply unnecessarily?

Originally Posted by Fordy

@tony2011

Grumpy wasn't trying to be offensive, its just that many people come here and expect homework/assignments to be done for them. That's not why we are here, so if someone doesn't do everything for you and then wants you to show more effort before doing more, then that's nothing for you to get upset about: it's how it is here.

there is a polite way to say everything. I didn't ask anyone to write any code for me. I just asked a doubt in a code snippet that I found in a book(which has some wrong answers). If google could clear my doubts, I wouldn't be posting them here.

Originally Posted by grumpy

The loop will terminate when scanf() returns zero. Look up the documentation for scanf() to discover the conditions in which scanf() will return zero.

Yes, I realise that is not answering your question. However, I have provided enough of a hint so you should be able to work out the answer for yourself.

Also, main() returns int, not void.

This is just a code snippet given in a book. So, i just have to work out with whats given. What difference does it make if the return type is int or void here?

Tony, welcome to the forum!

The great thing about programming is that you can simply print out the answer that you're looking for:

Code:

int number;
printf("Enter an integer: \n");
printf("%d", scanf("%d",&number));

put that into a program and see what you get for the return from scanf(). Now what would the return be from fscanf(), on a file number?

What about a string? A char?, A floating point number?

We're glad to have you here, but also want to encourage that sense of exploration that every professional should have.

Originally Posted by tony2011

I just wanted someone to clear my doubt. I didn't invite you to this thread and asked you to spoonfeed me. If you do not know the answer, why do you post the reply unnecessarily?

Grumpy gave you a perfectly good answer... "Look it up"...

Looking in reference materials for information is a skill all programmers must cultivate at some point in time. On a typical day I spend half my time (or more) looking up the correct syntax and other information about function calls. This is very simply because there's just too much for any one person to even hope to memorize correctly...

Why don't you see expert programmers (like Grumpy) on here begging for answers then getting upset when they don't get the exact response they wanted? Because they know how to and are willing to look up the information on their own.

Originally Posted by tony2011

This is just a code snippet given in a book. So, i just have to work out with whats given. What difference does it make if the return type is int or void here?

It matters because even if it's just a little "test program" it is still a program and the operating system has certain expectations of it's behaviour. There is no excuse for sloppy work...

Originally Posted by CommonTater

Grumpy gave you a perfectly good answer... "Look it up"...

Looking in reference materials for information is a skill all programmers must cultivate at some point in time. On a typical day I spend half my time (or more) looking up the correct syntax and other information about function calls. This is very simply because there's just too much for any one person to even hope to memorize correctly...

Why don't you see expert programmers (like Grumpy) on here begging for answers then getting upset when they don't get the exact response they wanted? Because they know how to and are willing to look up the information on their own.

Here we go again. Another unwanted reply. Guess there aren't any real programmers around here. I can see only people giving advices. And, I am not begging you 'Please help me! Please help me!' I posted a snippet and asked for a clarification. If you know the answer and of you are willing, post the explanation. Else, keep your figers away from the keyboard. Don't reply unnecessarily just to increase your post count.

Originally Posted by CommonTater

It matters because even if it's just a little "test program" it is still a program and the operating system has certain expectations of it's behaviour. There is no excuse for sloppy work...

What is your problem? Did you read my question? Did you understand it? Don't reply just for the sake of it.