Q40738: C memcpy and Large Model

Article: Q40738
Product(s): See article
Version(s): 5.10
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# G881031-5486 | mspl13_c
Last Modified: 16-MAY-1989

Question:

I normally compile a certain program with the /Ox switch. Inside a few
modules, I use the #pragma function(memcpy) statement, to force the
use of the function version of memcpy, which is required because I use
memcpy with some huge pointers.

This works correctly, until I want to use CodeView. At that time, I
recompile with the switches /Od /Zi. This produces the following error
message:

   Error C2164: 'memcpy': intrinsic was not declared

Editing each module to remove the #pragma function(memcpy), which is
not required in the /Od case, eliminates the error message. Editing
the pragma in and out is a lot of work, however.

Why is this required?

Response:

The C2164 error message is listed in ERRMSG.DOC, which is supplied
with the compiler. (It's a good idea to print out all the .DOC files
for reference; there's a lot of important information there that
doesn't appear in the manuals.) When you don't use the -Oi or -Ox
option, you need to declare a function prototype before you can use
the function or intrinsic pragmas. An easy way to do this is to
include the appropriate .H file: in this case, either STRING.H or
MEMORY.H will do. This will work with or without intrinsics.

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