CODEWITHSUNDEEP
g++cygwinpoco
daparic
daparic

Reputation: 4474

How did Cygwin g++ resolve it?

I am puzzled how a mere g++ -o testpoco testpoco.cpp -lPocoFoundation was able to compile successfully in my Cygwin environment. The complete C++ code is below:

#include <Poco/File.h>

int main (int argc, char *argv[])
{
    Poco::File f("/tmp/test.log");
    if (f.exists()) {
        return 1;
    }
    return 0;
}

I installed the cygwin Poco development headers and libraries and I verified they are in:

But without specifying those include and library path in g++ how did it was able to compile and produce the exe? I checked the output of g++ -v and did not see any routes to Poco.

Upvotes: 1

Views: 284

Answers (2)

Jonathan Wakely
Jonathan Wakely

Reputation: 171413

I checked the output of g++ -v and did not see any routes to Poco

The command g++ -v will just print out some version information about GCC, and how it was configured. Adding the -v option to your real commands used for compiling and/or linking will show the search paths for headers and libraries.

In other words, instead of just g++ -v you should try:

g++ -o testpoco testpoco.cpp -lPocoFoundation -v

This will show the search paths that Keith Thompson refers to in his answer.

Upvotes: 1

Keith Thompson
Keith Thompson

Reputation: 263617

The compiler has default search paths for include files and for libraries. (Actually the latter applies to the linker, not the compiler, but the g++ command invokes both.)

/usr/include and /usr/lib are in those default search paths.

You specified #include <Poco/File.h>, so the compiler found /usr/include/Poco/File.h.

You specified -lPocoFoundation, so the linker found /usr/lib/libPocoFoundation.dll.a, the file that contains the code implementing the PocoFoundation library under Cygwin.

Upvotes: 2

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