[vox-tech] C-Newbie needs help with a source-code

[Nicole TWN]

At 06:06 AM 10/30/2003, you wrote:
>what the program is about: you may input a decimal number and the program 
>will convert it into a dual number... after this it will determine the 
>length of the dual number (bestimme_laenge() ) then it should declare an 
>array Dec[] with last position --> lange-1 then the positions Dec[i] ... 
>i++ were filled in while while() after this it shut put out the positions 
>of the array from Dec[lange] to Dec[0] so that the dual number is in the 
>right order... but there are more numbers in the output the array shoul be 
>long... o.O thats what i don't understand... i hope you can help me with 
>this prob... greetz DaRkI sorry, my english is bad.. i know... but I hope 
>you'll understand what i mean ;)


OK, but you're not giving us a whole lot to work with here.  Let's break 
this into smaller problems.

So: you need to convert a decimal number into a binary number, then fill a 
variable-length array with the binary digits?  And you don't know how big 
it's going to be?
Now, the problem here is that plain C will not allow you to declare new 
variables in the middle of a program (though C++ will).  Your question 
seems to be: how do I know how big to make it?  I can think of two 
different approaches:
1. Dynamic memory allocation.  At the top of your program, declare a 
pointer (int *i) or an empty array (int i[]).  Once you know how big the 
binary number is going to be, use malloc() to assign some memory to that 
pointer.
2. Use your brain.  What's the biggest number a single integer variable can 
store?  Why?  How is this related to the largest size your array will ever 
be?  Hint: look up sizeof(int) on your computer.

Hope this helps.

--nicole twn