Why is the size of a character literal in C different than in C++

Question

I know that every literal in C and C++ get a specific type information. I have written this little program in C and compiled this in Visual Studio 2012. The source file is called 'main.c'.

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

Output:

sizeof(char) = 1
sizeof('i') = 4

I wondered that the size of a character wasn't 1 Byte. I renamed the source file to 'main.cpp' and now sizeof('a') returned 1 as previously expected. So there must be a language specific difference. Why is the size of a char in C 4 Byte and not 1 ?

*Q: Why is the size of a char in C different than in C++?* A: It isn't. — David Heffernan, Jan 05 '15 at 16:25

score 10 · Answer 1 · answered Jan 05 '15 at 16:24

10

Because in C++ the type of character literals is char, while in C it is int. Of course sizeof(char) itself is 1 in both languages by definition.

answered Jan 05 '15 at 16:24

Jon

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*Why is the size of a character literal in C different than in C++?* Your answer is *in C++ the type of character literals is char, while in C it is int*. I guess the underlying OP question is: why is a character literal `int` in C and not `char` as in C++. – ouah Jan 05 '15 at 16:49
@ouah: I can't agree with that. The question says "why is the size of a char....", which clearly highlights a misconception: that a character literal is of type `char`. One would need to clear that up before being in the position to ask why it happens. – Jon Jan 05 '15 at 16:54

score 5 · Accepted Answer · answered Jan 05 '15 at 16:25

In C, 'i' has type int for backwards-compatibility reasons. Thus sizeof('i') shows the size of an int on the chosen compilation platform.

In C++, because overloading made it more urgent to avoid giving surprising types to expression, it was decided to break backwards compatibility and to give 'i' the type char.

Why is the size of a character literal in C different than in C++

2 Answers2