*(char*)0 = 0; - What Does the C++ Programmer Intend with This Code? [video]

Re:*(char*)0 = 0; - What Does the C++ Programmer Intend with... by _kst_ on Tuesday October 17, 2023 @09:02PM (#37923675)

You can't assume char is one octet. It is one byte by definition.

A byte is CHAR_BIT bits, where CHAR_BIT >= 8. (It's exactly 8 on most implementations; DSPs are the most common exception).

short and int are both required to be at least 16 bits wide. It's possible for int to be 1 byte (sizeof (int) == 1), but only if CHAR_BIT >= 16.

[ Parent | on HN ]

Re:*(char*)0 = 0; - What Does the C++ Programmer Intend with... by _kst_ on Wednesday October 18, 2023 @01:27AM (#37925115)

A clarification: You can certainly assume that char is 8 bits if you don't mind losing portability to a small minority of systems.

If I'm being pedantic, I might add something like

    #if CHAR_BIT != 8
    #error "This code assumes 8-bit char"
    #endif

But realistically, if I'm using headers defined by either POSIX or Windows, that's probably enough of a guarantee. (Though I'd still use CHAR_BIT rather than 8 to refer to the number of bits in a byte.)

[ Parent | on HN ]

Re:*(char*)0 = 0; - What Does the C++ Programmer Intend with... by gpderetta on Wednesday October 18, 2023 @07:17AM (#37927137)

posix indeed guarantees CHAR_BIT == 8.

[ Parent | on HN ]