Random number generation from a vector of numbers

Question

I have a vector v = {1,5,4,2}. Now I want to write a function that returns a random pair of numbers from this vector. Example: {1,2},{4,4},{2,5},{5,1},{1,5},{2,2}....... I want this pair to be generated in a random manner. Any idea how to implement this ?

Answer 1

auto pair = std::make_pair(v[rand() % v.size()], v[rand() % v.size()]);

is one way.

Switch out rand() to something from the new <random> library of C++11 if you require the generator to have better statistical properties: aside from the generator itself, the use of % can introduce a statistical bias.