MATLAB: Help on .cpp mex file. Compile failed!

mexmex compiler

Hello,
I used to use MATLAB R2008b to do my work and now I've just installed MATLAB R2012b in my new computer. I have a file name rir_generator.cpp that I want to use in MATLAB. So I've tried setting it up as below, and this is what I got. I'm not really an expert on this and I don't know why it's failed. Can someone please help??
mex -setup
The options files available for mex are:
1: /Applications/MATLAB_R2012b.app/bin/mexopts.sh : 
    Template Options file for building gcc MEX-files
0: Exit with no changes
Enter the number of the compiler (0-1): 1
Overwrite /Users/username/.matlab/R2012b/mexopts.sh ([y]/n)? y
/Applications/MATLAB_R2012b.app/bin/mexopts.sh is being copied to /Users/username/.matlab/R2012b/mexopts.sh
mex rir_generator.cpp
/Applications/MATLAB_R2012b.app/bin/mex: line 305: gcc-4.2: command not found /Applications/MATLAB_R2012b.app/bin/mex: line 1326: g++-4.2: command not found
    mex: compile of ' "rir_generator.cpp"' failed.
Error using mex (line 206) Unable to complete successfully.
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