The most efficient way to reverse a number

Question

I am looking for an efficient algorithm to reverse a number, e.g.

Input: 3456789

Output: 9876543

In C++ there are p

Answer 1

Something like this will work:

#include 

int main()
{
    long in = 3456789;
    long out = 0;
    while(in)
    {
        out *= 10;
        out += in % 10;
        in /= 10;
    }
    std::cout << out << std::endl;
    return 0;
}