auto decltype
时间: 2023-10-22 09:15:37 浏览: 36
`auto` is a keyword in C++ that allows the compiler to automatically deduce the data type of a variable based on its initialization value.
`decltype` is another keyword in C++ that allows the programmer to obtain the data type of an expression at compile-time without actually evaluating the expression.
Together, `auto` and `decltype` can be used to simplify code and reduce the amount of manual type declarations required. For example:
```
auto x = 5; // Compiler deduces that x is an int
decltype(x) y = 10; // Compiler deduces that y is also an int
```
In this example, `auto` is used to automatically deduce the data type of `x` based on its initialization value of 5. Then, `decltype(x)` is used to obtain the data type of `x` (which is `int`) and use it to declare `y` as an `int` as well.