Difference between std::pair and std::tuple with only two members?

Is there a difference between an std::pair and an std::tuple with only two members? (Besides the obvious that std::pair requires two and only two members and tuple may have more or less...)

Solution 1:

There are some differences:

1. std::tuple is not required by the standard to ever be standard-layout. Every std::pair<T, Y> is standard-layout if both T and Y are standard-layout.

2. It's a bit easier to get the contents of a pair than a tuple. You have to use a function call in the tuple case, while the pair case is just a member field.

But that's about it.

Solution 2:

An std::tuple's name is longer (one extra character). More of those characters are typed with the right hand, so easier for most people to type.

That said, std::pair can only have two values - not zero, one, three or more. TWO values. A tuple, however, has almost no semantic limitation on the number of values. An std::pair, therefore, is a more accurate, type safe type to use if you actually want to specify a pair of values.