Article: Q46947
Product(s): See article
Version(s): 5.10 | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | SR# G890706-22068 | mspl13_c
Last Modified: 26-JUL-1989
Question:
When I compile the following program
1: void main(void)
2: {
3: char String[10];
4: char *s;
5:
6: s = &String;
7: }
using Version 5.10 and the command line
cl -W3 karma.c
the compiler generates the following message:
karma.c(6) : warning C4046: '&' on function/array, ignored
This is consistent with historical C behavior. However, I understand
that ANSI C considers array names to be lvalues. The July 1989 MSJ
article "Pointers 101: Understanding and Using Pointers in the C
Language" validates this assumption. Does this mean that the "&" in
"&String" is no longer benign? Under ANSI C, does this give me (in
effect) a pointer to the address of "String"? What is the type and
value of the expression "&String"?
Response:
The 5.10 compiler ignores the "&", so the type of "&String" is the
same as "String", which is "pointer to char." This represents common
pre-ANSI behavior.
ANSI requires that the type of "&String" now be "pointer to array of
10 char." The next version of Microsoft C will conform to this
requirement.
However, aside from type warnings that may occur, this change IS
benign because the address generated is identical in either case --
the address of the zeroth element of the array. In other words, it
will not somehow generate the address of the address -- especially
since the address is a constant.