/in/ex4.cpp: In member function 'virtual void bookInventory::removeBook(int)':
/in/ex4.cpp:79:27: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
     for (int i = index; i < numBooks - 1; ++i) {
                         ~~^~~~~~~~~~~~~~
/in/ex4.cpp:86:14: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
    if (index == numBooks) {
        ~~~~~~^~~~~~~~~~~
cc1plus: all warnings being treated as errors
/in/compile/Makefile:26: recipe for target 'ex4.o' failed
make: *** [ex4.o] Error 1