How many bytes does a #define string (string literal) take?

Question

#define STR "test1"

Why does this take 6 bytes?

sizeof(STR) = 6

Answer 1

There is a trailing '\0' at the end.

Answer 2

a #define just does a text replacement before compiling.

#define STR "test1"
sizeof(STR);

is actually seen by the compiler as

sizeof("test1");

now why is that 6 and not 5? because there's a null terminator at the end of the string.