In c++, typeid can accept the class name as the input. If I also want to implement a similar function, just like:
void func(T class)
{
std::cout<< typeid(class).name() <<std::endl;
}
What should be the T?
Update
I am sorry for this unclearing question. And more details are provided in the following.
I want to use it as:
class A
{
};
void main()
{
func(A);
}
I want func(A) can print the name of A just like std::cout<< typeid(A).name() <<std::endl;.
how to define a function using class name as the input parameters
Functions do not take types as parameters.
I know what template is, and what I want is not template. I hope the function can be used as func(A), where A is a class.
typeid is not a function, it is a built-in operator. How it is implemented is beyond your reach.
What you can do is write a function template that can be instantiated with different types:
template <typename T>
void func() {
std::cout<< typeid(T).name() <<std::endl;
}
This is a template and func<A> is a function (a specialization of the template) that can be called like this:
func<A>();
Or if you like to keep the signature of your func:
template <typename T>
void func(const T& t) {
std::cout<< typeid(t).name() <<std::endl;
}
Then you can call it like this:
SomeType t;
func(t);
typeid is an operator? How to implement myself func operator? Could you please provide an example?
typeid.
An alternative if you really don't want to use the much nicer func<A>() as suggested in this answer could be to make a macro. It won't make func into an actual function. It's more or less a "search and replace" instruction to the preprocessor.
#include <iostream>
#include <typeinfo>
#define func(T) do { std::cout << typeid(T).name() <<std::endl; } while(false)
This can now be used like you wanted:
class A {};
int main() {
func(A); // do { std::cout << typeid(A).name() <<std::endl; } while(false);
}
func is not a function. It is a function-like macro. And the difference is not just the ability to pass a type as parameter. For example it is not possible to get a function pointer.
classis a keyword in C++. It can't be used as the name of variables or other things.