Code highlighting, add more examples (#220)

README.md

@@ -25,18 +25,26 @@ Additionally, anything after `--` will be parsed as a positional argument.
 
 ## Basics
 
-    #include <cxxopts.hpp>
+```cpp
+#include <cxxopts.hpp>
+```
 
-Create a cxxopts::Options instance.
+Create a `cxxopts::Options` instance.
 
-    cxxopts::Options options("MyProgram", "One line description of MyProgram");
+```cpp
+cxxopts::Options options("MyProgram", "One line description of MyProgram");
+```
 
 Then use `add_options`.
 
-    options.add_options()
-      ("d,debug", "Enable debugging")
-      ("f,file", "File name", cxxopts::value<std::string>())
-      ;
+```cpp
+options.add_options()
+  ("d,debug", "Enable debugging") // a bool parameter
+  ("i,integer", "Int param", cxxopts::value<int>())
+  ("f,file", "File name", cxxopts::value<std::string>())
+  ("v,verbose", "Verbose output", cxxopts::value<bool>()->default_value("false"))
+  ;
+```
 
 Options are declared with a long and an optional short option. A description
 must be provided. The third argument is the value, if omitted it is boolean.
@@ -44,12 +52,16 @@ Any type can be given as long as it can be parsed, with operator>>.
 
 To parse the command line do:
 
-    auto result = options.parse(argc, argv);
+```cpp
+auto result = options.parse(argc, argv);
+```
 
 To retrieve an option use `result.count("option")` to get the number of times
 it appeared, and
 
-    result["opt"].as<type>()
+```cpp
+result["opt"].as<type>()
+```
 
 to get its value. If "opt" doesn't exist, or isn't of the right type, then an
 exception will be thrown.
@@ -80,7 +92,9 @@ vector to the `help` function.
 Positional arguments can be optionally parsed into one or more options.
 To set up positional arguments, call
 
-    options.parse_positional({"first", "second", "last"})
+```cpp
+options.parse_positional({"first", "second", "last"})
+```
 
 where "last" should be the name of an option with a container type, and the
 others should have a single value.
@@ -92,12 +106,16 @@ An option can be declared with a default or an implicit value, or both.
 A default value is the value that an option takes when it is not specified
 on the command line. The following specifies a default value for an option:
 
-    cxxopts::value<std::string>()->default_value("value")
+```cpp
+cxxopts::value<std::string>()->default_value("value")
+```
 
 An implicit value is the value that an option takes when it is given on the
 command line without an argument. The following specifies an implicit value:
 
-    cxxopts::value<std::string>()->implicit_value("implicit")
+```cpp
+cxxopts::value<std::string>()->implicit_value("implicit")
+```
 
 If an option had both, then not specifying it would give the value `"value"`,
 writing it on the command line as `--option` would give the value `"implicit"`,
@@ -134,6 +152,39 @@ The string after the program name on the first line of the help can be
 completely replaced by calling `options.custom_help`. Note that you might
 also want to override the positional help by calling `options.positional_help`.
 
+
+## Example
+
+Putting all together:
+```cpp
+int main(int argc, char** argv)
+{
+    cxxopts::Options options("test", "A brief description");
+
+    options.add_options()
+        ("b,bar", "Param bar", cxxopts::value<std::string>())
+        ("d,debug", "Enable debugging", cxxopts::value<bool>()->default_value("false"))
+        ("f,foo", "Param foo", cxxopts::value<int>()->default_value("10"))
+        ("h,help", "Print usage")
+    ;
+
+    auto result = options.parse(argc, argv);
+
+    if (result.count("help"))
+    {
+      std::cout << options.help() << std::endl;
+      exit(0);
+    }
+    bool debug = result["debug"].as<bool>();
+    std::string bar;
+    if (result.count("bar"))
+      bar = result["bar"].as<std::string>();
+    int foo = result["foo"].as<int>();
+
+    return 0;
+}
+```
+
 # Linking
 
 This is a header only library.