Thread: How to check a variable to make sure it is the correct data type?

I have checked out lots of sources from the internet but i cant find the exact way how to do it.

But i do found something like this:

Code:

#include <iostream>

int main() 
{  
  double d;
  cin>>d;
  if ( !cin.fail() )
    cout<<"Valid data type"<<endl;
  else
    cout<<"Invalid data type"<<endl;
  return 0;
}

I'm a beginner, not sure about it, but i think that is C++.

Is anyone know how to do it in C? Please help. Thanks in advanced!