Compatibility With Other C Compilers

 As noted above MSC 5.x with the Large Memory Model, Alternate Math
 Library is the most compatible C compiler for use with Clipper Summer
 '87 and 5.0x versions.  This does not mean that other vendor's C
 compilers can not be used with Clipper.  But there are additional
 limitations that must be observed when using these products.  When I
 started this article I wanted to demonstrate that non-MSC products
 could be used with Clipper very effectively.  Prior to working at
 Nantucket, I had always used Turbo C, and was able to accomplish most
 of what I wanted to do (using Summer '87 at that time.)  By the time
 I was done getting all the different products to compile and link -
 resolving all the little problems - I began to really appreciate the
 MSC  compiler.  If asked now, I think it is the only compiler I would
 recommend for use with Clipper.

 Table 1 shows the compatibility of some of the frequently asked about
 C compilers, along with the compiler command line switches that
 correspond to those recommended in the extend system documentation.
 The two products below, however, defy this table's simple
 categorization - so they are explained here in detail.

 C++ Extensions

  The way in which C++ implements method and operation overloading
  is by using a mechanism  referred to as "symbol table mangling".
  This means that if you have three object classes that all  have
  a display() method,  C++ changes the symbol for each version of
  "display",  into something  that tells it which of the three
  "display" methods it is referring to.

  It is possible to produce compatible C++ functions by defining
  the function as:

  extern "C" CLIPPER func ( void )

  This is a C++ declaration that tells the compiler not to
  "mangle" the name.  But since this turns  the function name into
  a normal "C" symbol,  you can not have function overloading,
  which limits  their usefulness as C++ functions.

 Microsoft C 6.0

  Microsoft, with the introduction of MSC 6.0, has renamed some of
  the math and stack checking  functions calls so that the code
  produced by the compiler is not backwardly compatible with MSC
  5.x library code.   The solution is to compile with the /Gh
  switch - which produces 5.x compatible  library calls - and then
  link with the 5.x LLIBCA library (assuming you have a copy of
  the MSC 5.x  LLIBCA).   If you do not have access to a 5.x
  version of LLIBCA, you can contact Microsoft  Technical Support
  and ask for the "downgraded" (5.x compatible) library.

  Also new in MSC 6.0 is the inclusion of a new compiler
  optimization that uses "intrinsic" routines.   These are
  routines that the compiler resolves into in-line assembly code
  instead of producing a  call to the library function.  Examples
  of intrinsic functions are strcpy and strcmp.  A list of
  functions that can be resolved to intrinsic forms is contained
  in Figure 1.

  There are two ways to cause a function to be resolved to an
  intrinsic:  by using the compiler  directive #pragma intrinsic(
  <function>, ... ) or by compiling with the /Oi (optimize with
  intrinsic  forms) switch .  If your C function uses only
  intrinsic functions you do not have to link in the C  library -
  and would not suffer from the library incompatibility described
  above.