How we can compile the Json-cpp library without scons build tools. I want compile this for vacpp.
Is there a way to create makefiles to compile the source code without the scons build scripts.

I want to know it also.

You can simply take my patch which adds cmake support (https://sourceforge.net/tracker/?func=detail&aid=3527408&group_id=144446&atid=758828), and type:
mkdir build/
cd build/

Generate the makefiles:
cmake -G "Unix Makefiles" ..
Or if on windows : cmake -G "MinGW Makefiles" ..
make

I'm obviously doing something wrong.

I applied the patch while in the jsoncpp-src-0.5.0 directory. I determined this to be the correct patch path because that's the parent directory of the files being patched.

I then ran the commands you listed above (for Xcode instead of Unix), but got errors. cake is looking for CMakeLists.txt in the current directory which is currently the empty build directory just created.

Any hints as to what's wrong?

If you didn't get any error by applying the patch, it should work correctly. Did you really run cmake .. (notice the .. to go to the parent dir containing the CMakeLists.txt). You can also try running cmake /path/to/jsoncpp-src-0.5.0/ , give me the output of this.

Additionally, it could be something I missed that doesn't run on Mac, as I don't have one to test, but I would be happy to debug this together.