Newbie need help in repeating a program after user input

Hi,i am currently having problem with the following code. I want the program to ask the user whether he wants to repeat himself at the end of the program.This is what i come up with and i am not sure why it doesn't work.Hope u all can help me.THANK!

Code:

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#include <stdio.h>

int main(void){
int age;
char answer;

do{
    printf("Please enter a number between 1 and 100.\n");
    scanf("%d", &age);
if (age>= 1 && age<= 20 )
    printf("you are very young\n");
else if (age> 20 && age<= 50 )
    printf("you are old\n");
else {
    printf("u are very old\n");
}
    printf("Do u want to continue?\n");
    scanf("%c",&answer);
    printf("\n");

}while (answer ='Y');

}

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Do you know the difference between = and ==?


--
Mats

Quote:

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Originally Posted by matsp

Do you know the difference between = and ==?


--
Mats

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Sorry, am not really that that sure when should use = and ==, i only know i have to use = when declaring variable?

Then you probably didn't write

Quote:

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

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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:

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

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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.

--
Mats

Quote:

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Originally Posted by matsp

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.

--
Mats

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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!

Quote:

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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!

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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