First place to look would be the examples that are included with CPLEX studio when you install it. On my windows 7 PC the CPLEX examples are in:
C:\Program Files (x86)\IBM\ILOG\CPLEX_Studio1251\cplex\examples
while the OPL examples are in:
C:\Program Files (x86)\IBM\ILOG\CPLEX_Studio1251\opl\examples\opl
There are lots of examples there, particularly the CPLEX examples, including what you are looking for in C++, Java, C# etc...