Size of character ('a') in C/C++

Question

What is the size of character in C and C++ ? As far as I know the size of char is 1 byte in both C and C++.

In C :

#include <stdio.h>
int main(){
  printf("Size of char : %d\n",sizeof(char));
  return 0;
 }

In C++ :

#include <iostream>
int main(){
  std::cout<<"Size of char : "<<sizeof(char)<<"\n";
  return 0;
 }

No surprises, both of them gives the output : Size of char : 1

Now we know that characters are represented as 'a','b','c','|',... So I just modified the above codes to these:

In C :

#include <stdio.h>
int main(){
  char a = 'a';
  printf("Size of char : %d\n",sizeof(a));
  printf("Size of char : %d\n",sizeof('a'));
  return 0;
 }

Output :

Size of char : 1
Size of char : 4

In C++ :

#include <iostream>
int main(){
  char a = 'a';
  std::cout<<"Size of char : "<<sizeof(a)<<"\n";
  std::cout<<"Size of char : "<<sizeof('a')<<"\n";
  return 0;
 }

Output :

Size of char : 1
Size of char : 1

So my question is : why the sizeof('a') returns different values in C and C++ ?

Answer 1

In C, the type of a character constant like 'a' is actually an int, with size of 4. In C++, the type is char, with size of 1. This is one of many small differences between the two languages.