2-3. Using Type Deduction

Type Deduction 发生在编译时期

可以对一般类型，自定义类型进行类型自推导

下面有两个例子：

１． Using auto with a class

 #include <iostream>
 #include <typeinfo>

 using namespace std;

 class MyClass
 {
 };

 int main()
 {
     auto variable = MyClass();
     cout << "Type of variable: " << typeid(variable).name() << endl;
     return ;
 }

２．Using auto with Uniform Initialization

#include <iostream>
#include <typeinfo>
using namespace std;

class MyClass
{
};

int main()
{
    auto variable{  };
    cout << "Type of variable: " << typeid(variable).name() << endl;
    auto variable2{ MyClass{} };
    cout << "Type of variable: " << typeid(variable2).name() << endl;
    return ;
}

use auto for local variables as much as possible.　在局部变量的时候使用auto