Large integer implementation

Why do many large integer libraries store their data as a string of symbols instead of a block of integers native to the system? It seems to me that this would make bitwise operations rather difficult to implement.

Stop trying to implement RSA and get someone else to do your homework for you.

GMP uses an array of machine words for speed reasons. GNU bc uses a char array of decimal digits.

To not answer your question, see The Art of Computer Programming, vol. 2: Seminumerical Algorithms by Donald Knuth.

I find this page informative: http://www.codeproject.com/KB/cs/biginteger.aspx