Mail Archives: cygwin/2004/11/03/16:30:13
On Wed, 3 Nov 2004, Rene Nyffenegger wrote:
> Hello
>
> I am trying to create a shared object and use it in a program under
> cygwin with gcc. I seem to miss a point. If some kind soul could help
> me on that, I'd be very grateful.
>
> Here's the code for the shared object (calc_mean.c):
>
> #include "calc_mean.h"
> double mean(double a, double b) {
> return (a+b) / 2;
> }
>
> Here's its header file (calc_mean.h):
>
> double mean(double, double);
>
>
> So, I compile that to a .so like so:
>
> $ gcc -shared -o libmean.so calc_mean.c
>
> Then, there's main.c that wants to use the shared object:
>
> #include <stdio.h>
> #include "calc_mean.h"
>
> int main(int argc, char* argv[]) {
> double v1, v2, m;
> v1 = 5.2;
> v2 = 7.9;
>
> m = mean(v1, v2);
>
> printf("The mean of %3.2f and %3.2f is %3.2f\n", v1, v2, m);
> return 0;
> }
>
> I try to compile main.c like so:
>
> $ gcc main.c -o main -L. -lmean
>
> However, the following error is returned:
> /usr/lib/gcc-lib/i686-pc-cygwin/3.3.3/../../../../i686-pc-cygwin/bin/ld:
> cannot find -lmean
> collect2: ld returned 1 exit status
>
> Obviously, I do something wrong here, but I have no idea what that could
> be.
As Chris recommended, use the ".dll" extension for your shared libs, or
you can also build an import lib using
$ gcc -shared -o libmean.so -Wl,--out-implib,libmean.dll.a calc_mean.c
and your link step should work.
Igor
--
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