C programming help required ....

[Thomas Condon]

Roger Oberholtzer wrote:

>On Fri, 2005-08-26 at 11:50 -0500, Ben Duncan wrote:
>  
>
>>It would be something they entered one time while setting up the file.
>>Probably will be done thru some sort of Data Entry routine so I can control
>>it.
>>    
>>
>
>That should present no trouble.  I bet your numbers were already
>conceptually compatible with the approach I suggested. It is just that
>you should use the scanf '%x' to read then from a user and '%x' to print
>them in ASCII. The actual integer is just used as is. Taking this
>approach allows you to use bit fields (mask/shift) instead of odd math
>to access the components in your numbers.
>
>  
>
The "odd" mathematical instructions to perform these two functions are:

Upper = (int)(value / 1000 )
Lower = value % 1000

That really doesn't seem all that difficult to me.

Dividing by 1000 essentially shifts right (but shifting only works 
evenly for powers of 2).  Casting the result to an int should not be 
necessary, but it has been my experience that I only get myself in 
trouble when I 'expect' the compiler designer to have done things right.

The "%" operator is "modulus", which is the remainder when the first 
number (value) is divided by the second (1000).  Modulus essentially 
masks the left half of the number, but bit masking only works for powers 
of 2, also.

No need to deal with hex at all.

Hope this helps.


Tom Condon