Create an example directory and add some code examples. (#944)

* update example directory

* modify some compile error.

* update with clang-format

* update

* update

* add_definitions("../include/json")

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# Date:      Wed Jul 10 21:26:16 2019 +0800
#
# On branch code_example
# Your branch is up-to-date with 'origin/code_example'.
#
# Changes to be committed:
#	modified:   example/CMakeLists.txt
#

* change CMakeLists.txt

* update streamWrite.cpp

* update

* Update readFromStream.cpp

* fix typo

example/CMakeLists.txt

@@ -0,0 +1,29 @@
+#vim: et ts =4 sts = 4 sw = 4 tw = 0
+cmake_minimum_required(VERSION 3.1)
+
+set(EXAMPLES
+	readFromString
+	readFromStream
+	stringWrite
+	streamWrite
+   )
+add_definitions(-D_GLIBCXX_USE_CXX11_ABI)
+set_property(DIRECTORY PROPERTY COMPILE_OPTIONS ${EXTRA_CXX_FLAGS})
+
+if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra ")
+else()	
+	add_definitions(
+	-D_SCL_SECURE_NO_WARNINGS
+	-D_CRT_SECURE_NO_WARNINGS
+	-D_WIN32_WINNT=0x601
+	-D_WINSOCK_DEPRECATED_NO_WARNINGS)
+endif()
+
+foreach (example ${EXAMPLES})
+	add_executable(${example} ${example}/${example}.cpp)
+	target_include_directories(${example} PUBLIC ${CMAKE_SOURCE_DIR}/include)
+	target_link_libraries(${example} jsoncpp_lib)
+endforeach()
+
+add_custom_target(examples ALL DEPENDS ${EXAMPLES})