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copied!<p>The problem is that on most <code>UNIX</code> platforms (unlike on <code>Win32</code> and <code>AIX</code>) all symbol references by default bind to the <em>first</em> definition of the symbol visible to the runtime loader.</p> <p>If you define <code>'operator new'</code> in the main <code>a.out</code>, everything will bind to that definition (as Neil Butterworth's example shows), because <code>a.out</code> is the very first image runtime loader searches.</p> <p>If you define it in a library which is loaded after <code>libC.so</code> (or <code>libstdc++.so</code> in case you are using <code>GCC</code>), then your definition will never be used. Since you are <code>dlopen()</code>ing your library after the program has started, <code>libC</code> is already loaded by that point, and your library is the very last one the runtime loader will search; so you lose. </p> <p>On <code>ELF</code> platforms, you may be able to change the default behavior by using <code>-Bsymbolic</code>. From <code>man ld</code> on Linux:</p> <pre><code> -Bsymbolic When creating a shared library, bind references to global symbols to the definition within the shared library, if any. Normally, it is possible for a program linked against a shared library to override the definition within the shared library. This option is only meaningful on ELF platforms which support shared libraries. </code></pre> <p>Note that <code>-Bsymbolic</code> is a linker flag, not a compiler flag. If using <code>g++</code>, you must pass the flag to the linker like this:</p> <pre><code> g++ -fPIC -shared library.cpp -o library.so -Wl,-Bsymbolic </code></pre>

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