Thread: Distinguishing types

Hi,

I was wondering if someone could help me.
I have a template function where based on the type passed in
I have to possibly access a struct member or just print the value.
Yet when I try to compile this it fails with tons of errors.

Code:

#include <typeinfo>
#include <iostream>

using namespace std;

typedef struct {
    double a;
    double b;
} A;

template<class E> void check_el(E val) {
  if(typeid(E) == typeid(int)) {
    cout << val << endl;
  } else if(typeid(E) == typeid(A)){
    double t = val.a;
    cout << t << endl;
  } else {
    cout << "NOTHING" << endl;
  }
}

int main() {
    A a = {1, 2};
    check_el<A>(a);
    check_el<int>(5);

    return 0;
}

How would I go about fixing this?

Thanks a lot for any help,
Tony

Instead of trying to implement a function that determines the type of data passed in, you will have more success outputting the data as you normally would with cout.

To do so you will merely need to provide an ostream << operator overloading function for each structure that handles its output.

Then, whenever you do something like:

Code:

A val;
val.a = 10;
val.b = 15;
cout << val << endl;

It will automatically output the structure as you implemented it with the overloaded function.

Thanks a lot for the suggestions and pointers guys.