Compile OpenCV sample convert_cascade.cpp (OpenCV 2.3) - opencv

Question

I'm running OpenCV 2.3.1 on Ubuntu 11.10. I can compile various program I've written myself wih no issue.
Now, however, I have a half-done Haar cascade, that I need to assemble into the xml-cascade file. For this purpose I need to use the included sample program convert_cascade.c. It is not compiled by default, so I need to do that.
Running gcc like this fails:
gcc -lopencv_core -lopencv_highgui -lopencv_objdetect -I/usr/local/include/opencv/ -L/usr/local/lib/ convert_cascade.c -o convert_cascade
It gives me the following errors:
/tmp/cc5UddX6.o: In function `cvRound':
convert_cascade.c:(.text+0x19): undefined reference to `lrint'
/tmp/cc5UddX6.o: In function `cvDecRefData':
convert_cascade.c:(.text+0xb3b): undefined reference to `cvFree_'
convert_cascade.c:(.text+0xbac): undefined reference to `cvFree_'
/tmp/cc5UddX6.o: In function `cvGetRow':
convert_cascade.c:(.text+0xca2): undefined reference to `cvGetRows'
/tmp/cc5UddX6.o: In function `cvGetCol':
convert_cascade.c:(.text+0xccd): undefined reference to `cvGetCols'
/tmp/cc5UddX6.o: In function `cvReleaseMatND':
convert_cascade.c:(.text+0xce0): undefined reference to `cvReleaseMat'
/tmp/cc5UddX6.o: In function `cvSubS':
convert_cascade.c:(.text+0xe00): undefined reference to `cvAddS'
/tmp/cc5UddX6.o: In function `cvCloneSeq':
convert_cascade.c:(.text+0xe4e): undefined reference to `cvSeqSlice'
/tmp/cc5UddX6.o: In function `cvSetNew':
convert_cascade.c:(.text+0xead): undefined reference to `cvSetAdd'
/tmp/cc5UddX6.o: In function `cvGetSetElem':
convert_cascade.c:(.text+0xf40): undefined reference to `cvGetSeqElem'
/tmp/cc5UddX6.o: In function `cvEllipseBox':
convert_cascade.c:(.text+0x1040): undefined reference to `cvEllipse'
/tmp/cc5UddX6.o: In function `cvFont':
convert_cascade.c:(.text+0x1090): undefined reference to `cvInitFont'
/tmp/cc5UddX6.o: In function `cvReadIntByName':
convert_cascade.c:(.text+0x111e): undefined reference to `cvGetFileNodeByName'
/tmp/cc5UddX6.o: In function `cvReadRealByName':
convert_cascade.c:(.text+0x11af): undefined reference to `cvGetFileNodeByName'
/tmp/cc5UddX6.o: In function `cvReadStringByName':
convert_cascade.c:(.text+0x1209): undefined reference to `cvGetFileNodeByName'
/tmp/cc5UddX6.o: In function `cvReadByName':
convert_cascade.c:(.text+0x1239): undefined reference to `cvGetFileNodeByName'
convert_cascade.c:(.text+0x124f): undefined reference to `cvRead'
/tmp/cc5UddX6.o: In function `main':
convert_cascade.c:(.text+0x13b6): undefined reference to `cvLoadHaarClassifierCascade'
convert_cascade.c:(.text+0x1495): undefined reference to `cvSave'
collect2: ld returned 1 exit status
It seems that all the missing functions areare old C-style OpenCV functions prototyped in core_c.h. But including that ( #include <opencv2/core/core_c.h> ) makes no difference. I also tried compiling with the -lopencv_legacy flag (basically just a guess that it might have something to do with older functions), to no avail.
What should I do in order to compile it?

Answer 1

There should be a build_all.sh script in the /samples/c/ directory that will build all the examples for you; no CMAKE tweaks required.

Answer 2

Nevermind. It turned out I had to recompile OpenCV anyway in order to enable TBB, so I simply gave CMAKE the BUILD_EXAMPLES=ON command, and now I have it in a compiled version. I'm pretty sure that is not the proper solution though ;-)