How is the auto keyword used in C++?

In C++11, the auto keyword is used to automatically deduce the type of a variable, allowing the compiler to infer the variable’s type based on its initialization expression, thereby simplifying code writing. The auto keyword is typically used to reduce redundancy in code, improve readability, and maintainability.

For example:

auto x = 10; // 编译器会自动推断x的类型为int
auto y = 3.14; // 编译器会自动推断y的类型为double

There are several points to keep in mind when using the auto keyword.

1. The keyword “auto” cannot be used for function parameters, function return values, class member variables, etc.
2. The variable type inferred by the auto keyword cannot be changed, meaning once a variable is declared using auto, its type cannot be modified.
3. The variable type inferred by the auto keyword can be a reference type but not a pointer type.
4. It is recommended to use the auto keyword in combination with the initialization expression following it to ensure that the compiler accurately infers the type of the variable.