[Courses] C Programming For Absolute Beginners, Lesson 2: Fun With Printf, Scanf, Puts, and Variables

[Sachin Divekar]

> /* addition; an example of adding and displaying user input */
>
> #include <stdio.h>
>
> int main()
> {
>    int a, b, c;
>
>    puts( "Please enter any number up to three digits: " );
>    scanf( "%d", &a );
>    puts( "Please enter another number up to three digits: " );
>    scanf( "%d", &b );
>    c = a + b;
>    printf("%d + %d = %d\n", a, b, c);
>
>    return 0;
> }
>
> When you run it it looks like this:
>
> $ addition
> Please enter any number up to three digits:
> 34
> Please enter another number up to three digits:
> 567
> 34 + 567 = 601
>


Hi,

I am really enjoying discussions on this course's mailing list.

Now towards the question.

I tried a very large input to addition program. Following was the result.

==========================================
sachin at sachin-ThinkPad-T420:~/projects/C$ ./addition
Please enter any number up to three digits:
1111111111111111111111111
Please enter another number up to three digits:
1111111111111111111111111111111111111111111111
-1 + -1 = -2
===========================================

A quick reading on Wikipedia about C data type "int" says,

"basic signed integer type. At least 16 bits in size."

So, what exactly "16 bits in size" means? I know 1 bit is either state
1 or 0. But how this(bits) determines size of number?

Thanks.

--
Regards,
Sachin