C++ Primer, Fifth Edition

9.2.7. Relational Operators

Every container type supports the equality operators (== and !=); all the containers except the unordered associative containers also support the relational operators (>, >=, <, <=). The right- and left-hand operands must be the same kind of container and must hold elements of the same type. That is, we can compare a vector<int> only with another vector<int>. We cannot compare a vector<int> with a list<int> or a vector<double>.

Comparing two containers performs a pairwise comparison of the elements. These operators work similarly to the string relationals (§ 3.2.2, p. 88):

• If both containers are the same size and all the elements are equal, then the two containers are equal; otherwise, they are unequal.

• If the ...