try these google links

Now I have problem with fmod...

i calculated with y=pow(a,e)

then fmod(y,n)... but now i seems that that fmod has to small range of results (same thing is with %)
is there some other function for mod?

Use the GMP library. It works for me. If you're using Dev-C++, you can just search for packages online with the built in "Check for updates/packages" thing, and find it in the list. If not go here: http://gmplib.org/

How to instal GMP library....dev c++ won'r downlod it, and i don't knoe how to install one i have downloaded from http://gmplib.org/

Talking about using a sledgehammer to crack a nut. No need to use high precision integers at all.

(a^b) mod c can be evaluated using a loop, using modulo arithmetic.

The basic property you need to know is that (x*y) mod z is equal to ((x mod z)*(y mod z)) mod z). From that it is possible to compute (a^b) mod c. I'll leave the precise code as an exercise.

Dev-C++ WILL download it. You have to pick the option in the package downloader that says community devpaks, scroll down and find it. Download it, and it should automatically bring you to an installer.

I tried to download it in that way...but i get some error that this file doesn't exist..

i figured out that i must use this kind calculations if i want to work with big nombers:
P = Cd % n
= 62^65 % 133
= 62 * 62^64 % 133
= 62 * (62^2)32 % 133
= 62 * 3844^32 % 133
= 62 * (3844 % 133)^32 % 133
= 62 * 120^32 % 133
.
.
.
= 62 * 36^16 % 133
= 62 * 99^8 % 133
= 62 * 92^4 % 133
= 62 * 85^2 % 133
= 62 * 43 % 133
= 2666 % 133
= 6


How can i write this in c++?
please help

i'll attack the devpak! =)

Try to express it as a loop construct. Your logic here is, mathematically, equivalent to what I said in my previous post.