Update global make with C++ instructions

README.md

@@ -42,13 +42,34 @@ try `export CPATH=/path/to/OpenCL/include` and `export LD_LIBRARY_PATH=/path/to/
 
 You can also run `make` in the Examples/ and Solutions/ high-level directory;
 this calls all the sub-directory make files so all the examples can be built in one command.
+This also builds all the C++ examples.
 
 Define the variable `DEVICE` in the Makefiles to be one of the OpenCL device types to vary the device type the C applications use.
 This can be done easily in the two global Makefiles found in the Exercises and Solutions directories.
 To use a GPU, for example, change the line `DEVICE = CL_DEVICE_TYPE_DEFAULT` to `DEVICE=CL_DEVICE_TYPE_GPU`.
 
 Note: you can also edit each of the source files to use a specific device type, but we would recommend using the global Makefile method above.
 
+Define the variable `CC` to change the C compiler used.
+By default, this is set to gcc for all platforms.
+
+**C++**
+
+You must first run `make` to build the binary.
+We assume that your environment is set up to find the OpenCL library.
+
+You can also run `make` in the Examples/ and Solutions/ high-level directory;
+this calls all the sub-directory make files so all the examples can be built in one command.
+This also builds all the C examples.
+
+Define the variable `DEVICE` in the Makefiles to be one of the OpenCL device types to vary the device type the C++ applications use.
+This can be done easily in the two global Makefiles found in the Exercises and Solutions directories.
+To use a GPU, for example, change the line `DEVICE = CL_DEVICE_TYPE_DEFAULT` to `DEVICE=CL_DEVICE_TYPE_GPU`.
+
+Note: you can also edit each of the source files to use a specific device type, but we would recommend using the global Makefile method above.
+
+Define the variable `CPPC` to change the C compiler used.
+By default, this is set to g++ on Linux, and clang++ on OS X.
 
 Directory structure
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