Data type of character constants in C and C++

In C, data type of character constants is int, but in C++, data type of same is char.  If we save below program as test.c then we get 4 as output (assuming size of integer is 4 bytes) and if we save the same program as test.cpp then we get 1(assuming size of char is 1 byte) 

C++

// C++ program demonstrating that data type of character
// constants in C++ is same as 'char'

#include <iostream>
using namespace std;

int main() {

    cout << sizeof('a');

    return 0;
}

// This code is contributed by sarajadhav12052009

C

#include <stdio.h>
int main()
{
  printf("%lu", sizeof('a'));

  getchar();
  return 0;
}

Output of C++ program:

1

Output of C program:

4

References: http://en.wikipedia.org/wiki/C_syntax#Character_constants