What is the method of referencing strings in C++?

In C++, strings can be referenced using references. References are a special data type in C++ that serve as aliases to existing variables, allowing for direct manipulation of the referenced variable.

To quote a string, you can use the quotation marks & to make the string type a reference type. For example:

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello, World!";
    std::string& ref = str;
    
    std::cout << ref << std::endl;  // 输出：Hello, World!
    
    ref = "Hello, C++!";
    std::cout << str << std::endl;  // 输出：Hello, C++!
    
    return 0;
}

In the above code, str is a string variable, and ref is a reference to str. Operations can be performed directly on str through the reference ref, and any changes made to ref will also affect str.

It is important to note that string references can modify the referenced string, but they cannot reference a temporary string. For example, the following code is incorrect:

std::string& ref = "Hello";  // 错误，不能引用临时字符串

This is because temporary strings are anonymous objects that do not have persistent memory space and therefore cannot be referenced.

In conclusion, the way to reference a string in C++ is by declaring the string type as a reference type and using the reference symbol & for declaration.