Up to now, our programs have explicitly indicated that each library name we use is in the
std namespace. For example, to read from the standard input, we write
std::cin. These names use the scope operator (
::) (§ 1.2, p. 8), which says that the compiler should look in the scope of the left-hand operand for the name of the right-hand operand. Thus,
std::cin says that we want to use the name
cin from the namespace
Referring to library names with this notation can be cumbersome. Fortunately, there are easier ways to use namespace members. The safest way is a
using declaration. § 18.2.2 (p. 793) covers another ...