How to convert from ZZ to ZZ_p in Number Theory Library?

Question

Using NTL, I have to evaluate a polynomial in some point and I have found eval function: void eval(ZZ_p& b, const ZZ_pX& f, const ZZ_p& a), but further in my program I have to use b as an exponent. The power function is like this: void power(ZZ_p& x, const ZZ_p& a, const ZZ& e).

Is there a way to convert from ZZ to ZZ_p?

Answer 1

I would say it is better to have ZZ_p and use rep:

ZZ_p p;
power(x, a, rep(p));

for the read-only const ZZ& representation of it. This way you avoid unnecessary ZZ -> ZZ_p parsing.