Add example for test compilation with the library.

Author: pavoljuhas

README.md

@@ -22,7 +22,7 @@ New calculator class can thus be readily defined for any quantity that is
 obtained by iteration over atom pairs.
 
 For more information see user manual at
-http://www.diffpy.org/doc/libdiffpy/.
+http://www.diffpy.org/doc/libdiffpy.
 
 
 ## REQUIREMENTS
@@ -36,18 +36,19 @@ libdiffpy library requires C++ compiler and the following software:
 Recommended software:
 
 * `libobjcryst` - C++ library of free objects for crystallography,
-  https://github.com/diffpy/libobjcryst/
-* `cxxtest` - CxxTest Unit Testing Framework, http://cxxtest.com/
+  https://github.com/diffpy/libobjcryst
+* `cxxtest` - CxxTest Unit Testing Framework, http://cxxtest.com
 
-Required software is usually available in the system package manager,
-for example, on Ubuntu Linux the dependencies can be installed as:
+On Ubuntu Linux the required software can be installed using the
+system package manager:
 
 ```sh
 sudo apt-get install \
     build-essential scons libboost-dev libgsl0-dev
 ```
 
-For Mac OS X machine with the MacPorts package manager one could do
+For Mac OS X machine with the MacPorts package manager the installation
+command is
 
 ```sh
 sudo port install scons boost gsl
@@ -68,6 +69,19 @@ This installs libdiffpy for all users under the `/usr/local` directory.
 If administrator (root) access is not available, see the usage info from
 `scons --help` for options to install to a user-writable location.
 
+To verify libdiffpy installation, compile and run the included
+test code [examples/testlib.cpp](examples/testlib.cpp)
+
+```sh
+cd examples
+c++ testlib.cpp -ldiffpy
+./a.out
+```
+
+If compilation fails because of missing header files or missing libdiffpy
+library, adjust the `CPATH` and `LIBRARY_PATH` environment variables or
+use the `-I` or `-L` compiler options.  If the libdiffpy shared library
+cannot be found at runtime, adjust the `LD_LIBRARY_PATH` environment variable.
 
 ## DEVELOPMENT
 

examples/testlib.cpp

@@ -0,0 +1,19 @@
+// Test program for checking the installation of libdiffpy shared library.
+// Compile and run this code using:
+//
+//      c++ testlib.cpp -ldiffpy
+//      ./a.out
+
+
+#include <iostream>
+#include <diffpy/srreal/ScatteringFactorTable.hpp>
+
+int main(int argc, char* argv[])
+{
+    using namespace diffpy::srreal;
+    ScatteringFactorTablePtr ntbl;
+    ntbl = ScatteringFactorTable::createByType("neutron");
+    ntbl->lookup("Pb");
+    std::cout << "Installation of libdiffpy shared library works!\n";
+    return 0;
+}