most efficient way of swapping values c++

Question

I was wondering what the most efficient, in terms of operations, way of swapping integers is in c++, and why? Is something like:

int a =..., b = ...;
a = a + b;
b = a - b;
a = a - b;

more efficient than using a temporary? Are there any other more efficient ways? (not asking for just other ways to swap the ints) and why would they be more efficient?

Answer 1

Assigning values is always faster than doing arithmetic operations.

C++ implementation for std::swap is

template<typename T> void swap(T& t1, T& t2) {
    T temp = std::move(t1); // or T temp(std::move(t1));
    t1 = std::move(t2);
    t2 = std::move(temp);
}

So to use a temporary variable is better than doing arithmetic trick.
And to use std::swap is even better because To reinvent the wheel in programming is never a good idea

Answer 2

The best way is to trust your compiler and use the C++ standard library functions. They are designed for each other.

std::swap will win.

You could use an XOR swap for an int (which doesn't require a temporary), but these days it would still perform less well than std::swap.