What will happen when we declare cin as int and take input from cin with print cin in cout?

Devendra Jadhav

#include <iostream>
using namespace std;
int main() {
    int cin;
    cin >> cin;
    cout << "cin is : " << cin;
}

In this code it gets different output in different complier and can't find proper solution.

zdf

There are two things you probably don't understand: scope and initialization.

In the code below the global variable v is hidden by local variable v declared in main. All operations in main are performed on main's v. The same is true for cin. The cin you declared in main is not the same cin declared in std namespace. So, cin >> cin; has a different meaning. You probably expected the same behaviour as std::cin >> cin;.
```
double v;
int main()
{
  int v;
}
```
c++ allows uninitialized variables. When you write int cin; memory space is allocated for cin, but nothing is written in (the variable is not automatically initialized). Leaving a variable uninitialized may be on purpose or not. Your compiler may be set to warn on uninitialized variables and/or check at run time. If you compile in debug configuration the variables may be automatically set to zero, depending on compiler, but you should not rely on this as your final build will be in release.