Common error message with "undefine reference to " of GCC

sybaselu

Hi guys
   The following is common failure message of GCC,however, Because I tried other ways to resolved this in vain(e.g edit to Makefile-->LBFLAGS= -I/lib -I/usr/lib and so on)
[root@root tiny_SAX2]# make
g++  -g -O2  -L/lib -L/usr/lib -L/usr/local/lib -o main  main.o  -lpthread
main.o(.text+0x38): In function `main':
/usr/lib/qt-3.3/include/qstring.h:840: undefined reference to `QString::shared_n ull'
main.o(.text+0x41): In function `main':
/home/Test_QT/tiny_SAX2/main.cpp:14: undefined reference to `vtable for Structur eParser'
main.o(.text+0x48):/home/Test_QT/tiny_SAX2/main.cpp:14: undefined reference to ` vtable for StructureParser'
main.o(.text+0x4f):/home/Test_QT/tiny_SAX2/main.cpp:14: undefined reference to ` vtable for StructureParser'
(..........)
Thanks and cheers

rickxbx

看样子是少链接了一些库

zhllg

Normally, this kind of problems are due to missing libraries when linking
To solve, you need to add the result of `pkg-config --libs package_name` to gcc's command line option
Possibly, you also need to add the missing library's path to gcc's  library searching path using "-L" option

PS: I recommend a little book called "An introduction to gcc", it should be useful to you