Question

I need to know a built-in function or anyway to get the type of a variable in C++

I want to check the type of the variable in a generic method.

for INSTANCE

template<class Numbers> bool Matrix(Numbers matrix[] ,int matrixsize)
{
 if (/* type of matrix is int */)
   return false;
 else
   return true;
} 

Answer 1

New answer

For as far as my decryption skills go, the comments made the question slightly more clear. What you want is template specialization.

template<class Numbers>
bool Matrix(Numbers matrix[] ,int matrixsize) {
  return true;
}

template<>
bool Matrix(int matrix[] ,int matrixsize) {
  return false;
}

---

Old answer

If you want to do this at compile time, in C++11 you can use decltype to get the type of any expression:

int my_variable;
decltype(my_variable) other_variable; // has type int

I’m not aware of any way to do this (easily) in C++03.

---

If you want to get the type of an object at runtime (which can be useful when dealing with polymorphism, sometimes), you can use the typeid() operator and std::type_info.

#include <type_info>
// ...

void foo(some_virtual_class& base) {
  const std::type_info& info = typeid(base);
  // Do something with the type info.
}