Tero Koskinen <[email protected]> writes:
> procedure printf (S : Interfaces.C.char_array; I : Interfaces.C.Int);
> pragma Import (C, printf, "printf");
This is _not_ guaranteed to work; see gnat user guide, 2.10.2 Calling
Conventions:
A note on interfacing to a C "varargs" function:
* In C, `varargs' allows a function to take a variable number of
arguments. There is no direct equivalent in this to Ada. One
approach that can be used is to create a C wrapper for each
different profile and then interface to this C wrapper. For
example, to print an `int' value using `printf', create a C
function `printfi' that takes two arguments, a pointer to a
string and an int, and calls `printf'. Then in the Ada
program, use pragma `Import' to interface to `printfi'.
* It may work on some platforms to directly interface to a
`varargs' function by providing a specific Ada profile for a
particular call. However, this does not work on all
platforms, since there is no guarantee that the calling
sequence for a two argument normal C function is the same as
for calling a `varargs' C function with the same two
arguments.
--
-- Stephe
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