bigint modpow

hello, im searching a function in c for modular exponentiation modpow using bigint.
i just find for c#, anyone can help?

By "bigint" you mean multiple precision arithmetic integer types?
Try libgmp.

i need this function

Code:

---

int power(int x, int exp, int n)
{
    int res = 1;      // Initialize result
 
    x = x % n;  // Update x if it is more than or 
                // equal to p
 
    while (exp > 0)
    {
        // If y is odd, multiply x with result
        if (exp & 1)
            res = (res*x) % n;
 
        // y must be even now
        exp = exp>>1; // y = y/2
        x = (x*x) % n; 
    }
    return res;
}

---

but whit type BIGINT instead int

There is no such built-in type named BIGINT. Refer to flp1969's post #2 for a library that can help.