Do string literals that end with a null-terminator contain an extra null-terminator?

Question

For example:

char a[] = "abc\0";

Does standard C say that another byte of value 0 must be appended even if the string already has a zero at the end? So, is sizeof(a) equal to 4 or 5?

Answer 1

All string literals have an implicit null-terminator, irrespective of the content of the string.

The standard (6.4.5 String Literals) says:

A byte or code of value zero is appended to each multibyte character sequence that results from a string literal or literals.

So, the string literal "abc\0" contains the implicit null-terminator, in addition to the explicit one. So, the array a contains 5 elements.