c++ - 头文件中类型名称的显式限定

Question

The C++ Programming Language 第 4 版的第 432 页介绍了桌面计算器的界面。 string 和 istream 之类的名称似乎是“裸露的”(没有 std 资格)。我可以在自己的声明中模拟这种行为吗，如下所示:

标题.h

// This is header.h

#include <string>
#include <vector>

extern string s; 
void func(vector<int> vi);

// and so on

...或者字符串和 vector 之类的名称是否需要明确限定？

Answer 1

书的第 89 页指出

For simplicity, I will rarely use the std:: prefix explicitly in examples. Neither will I always #include the necessary headers explicitly. To compile and run the program fragments here, you must #include the appropriate headers (as listed in §4.4.5, §4.5.5, and §30.2) and make the names they declare accessible.