Thread: Newbie need help in repeating a program after user input

Do you know the difference between = and ==?


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Mats

Then you probably didn't write

if (age>= 1 && age<= 20 )

did you?

Have a look at the tutorials on this website, or the list of books at the top of the C board.

I am fairly new to programming myself, but I noticed something about your code that I thought I would comment on.

What if the user answers with yes instead of 'Y'? Maybe you should clarify that they should input 'Y' or 'N'.

Whilst nitpicking:

Code:

    printf("Please enter a number between 1 and 100.\n");

Would it not be better to ask for "enter your age", rather than "enter a number ..." - if the user knows what the number is used for, it will help them input something that is meaningfull. If I get a prompt to enter a number 1-100, I may well enter 42 - but that's not my age [it's close, and the output would actually be the same - but still].

And to explain:
= assigns a value. E.g. a = 7;
== compares a value. E.g. a == 1 is true if a has the value 1.
Your while-condition sets answer to 'Y'. And because the way that C works, it then says "is the value we set answer to non-zero" - yes, then continue the loop. So I expect that your program loops forever, whatever the user inputs.

Your main should also end with "return 0;" to indicate that you successfully finished.

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Mats

Originally Posted by dragee

Thanks everybody for the help!
I dun really understand what u mean by this
" And because the way that C works, it then says "is the value we set answer to non-zero" - yes, then continue the loop."
Do u mean that the C will only not loop if the answer is zero?
I knew there is something wrong with my while function but i still dun really understand why doesn't compare correctly to my input.
Thanks!

In C, any condition (as in, if, while and similar), the determination of whether it is true or false is "if it's not zero, it's true".

So if you do "if (x = y)" then we are assiging x with the value of y, then checking if the "result" is zero - so if y is zero, then x is zero and the "result" is zero - that is, false. If y is not zero, then the whole thing is true.

Same with your "answer = 'Y'" - you are setting the variable answer to 'Y'. Since 'Y' is not the value zero, so the loop continues. (In ASCII/ANSI, 'Y' is 89 - there are other values that may generate the letter Y on some other computers, I'm 99.999% sure that there is not a single one where the letter 'Y' is zero - because zero is very very often used as a special character, such as marking the end of strings and such).

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Mats