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

c string standards
xiaokaoy picture xiaokaoy · Jul 30, 2013 · Viewed 15k times · Source

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

David Heffernan picture David Heffernan · Jul 30, 2013

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.

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