Size of Char in C

Hello,

I ran the following code in Visual C++ and I have 1 and 4
In GCC 11.2 I have 1 and 1

Why in Visual C++ do we have 4 for a character?

Thank you

1
2
3

 char c = '\0';
    printf("    sizeof c = %2zu\t       sizeof(char) = %2zu\n",
        sizeof c, sizeof('A'));

salem c (3700)

> sizeof('A')
It's one of the many differences between C and C++.
In C, this is the size of an integer, but in C++ it is the size of a character.
http://david.tribble.com/text/cdiffs.htm#C99-char-literal

Be mindful of whether you compile your test as C or C++.

Peter87 (11235)

Yeah, char literals in C have type int.

Just look at all the <ctype.h>/<cctype> functions such as tolower, isspace, etc. They all take an int as argument.

The type is less important in C because there is no function overloading and the promotion rules will automatically convert chars to ints when passing them to for example printf.

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jonnin (11437)

There may, back in the day, have been hardware reasons too. Some of the older cpus worked better with fixed sized chunks, the machine's 'word' size. This is a dim memory, not sure to be honest, but it was similar to how structs can be realigned by some compilers for performance reasons.

deleted account xyzzy (5768)

Why in Visual C++ do we have 4 for a character?

Microsoft.

Well, to be less flippant....

different C/C++ implementations, possible different data type sizes.

As others have pointed out, what A' is treated as being -- char/int -- differs.

seeplus (6591)

Not in VS C++ you don't. It's a char.

Compiled as C++:

#include <cstdio>

int main() {
	char c = '\0';

	printf("    sizeof c = %2zu\t       sizeof(char) = %2zu\n",
		sizeof c, sizeof('A'));
}


    sizeof c =  1              sizeof(char) =  1

But compiled as C code:


    sizeof c =  1              sizeof(char) =  4

But, as has been pointed out above, in C a char literal (eg 'A') has a type of int, not char. That's why in C sizeof('A') is 4 and not 1. The output is misleading as it's not showing sizeof(char), but sizeof (char_literal). In C++ they are the same. In C they are not.

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Peter87 (11235)

sizeof(char) is always 1.

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