c++ test if all items in an iteratable container are equal

all_equal.hxx

#include <algorithm>

template<typename T>
bool all_equal(const T& c)
{
    return c.empty() or std::equal(++c.begin(), c.end(), c.begin());
}

// Example:
// std::vector<int> v{42, 42, 42};
// all_equal(v); // returns true