I am hacking together a quick implementation of a rudimentary big number library. I am aware that there are plenty of those around, but mine is for a very specific purpose (I want it to work under the restrictions of C++ AMP). Besides, I figured that it would be a good exercise.

So, all of my arithmetic operations work (using basic textbook long multiplication and division). However, I am starting to get tired of thinking in binary. I would like to output my numbers in decimal digits. For integers, I have just implemented the naive approach.

str = "";
num = x;
do {
    digit = num%base;
    num = num/base;
    str = to_char(digit) + str;
} while (num>0);

Edit: Uhm, not sure where the rest of this went. Basically, my question was how to do the same for fixed point decimal numbers. I described an overly complicated solution and Álvaro whipped up the right answer straight away.

This isn't too hard. Print the integer part first, then a point, then take the fractional part, multiply it by 10 and print the integer part. Rinse, repeat.

Is that what you needed?

Oh, wow, thanks! Sometimes the simplest solutions just don't occur to me. I guess I didn't consider splitting up the integer and fractional parts.

Very nice and comprehensive implementation, iMalc! I can definitely learn from your code, especially things like the conversions from and to float etc...

Yes performance is important, so I try not to be wasteful. However, my library prioritizes readability over high optimization. Basically, this is just a toy project to play around with AMP and see what I can do with it. The string conversion is certainly not performance critical, since it is mainly for debugging purposes.