Major overhaul of C++ documentation

- Cleaned up and rephrased comments
- Removed old and erroneous information
- Normalized indentation to four spaces
- Normalized style to "Stroustrup style"
  (http://www.stroustrup.com/bs_faq2.html#layout-style)
- Added a section on references

In the near future I plan on additional sections covering idiomatic
use, such as RAII and C++11 paradigms.

c++.html.markdown

@@ -7,180 +7,153 @@ contributors:
 lang: en
 ---
 
-I am writing this to highlight the differences and
+C++ was designed as a systems programming language that
-additions that C++ has with respect to C. My
+
-suggestion would be to follow the C tutorial first
+- is a "better C"
-then look here for the additions and differences.
+- supports data abstraction
+- supports object-oriented programming
+- supports generic programming
+
+Though its syntax can be more difficult or complex than newer languages,
+it is widely used because it compiles to native instructions that can be
+directly run by the processor and offers tight control over hardware (like C)
+while offering high-level features such as generics, exceptions, and classes.
+This combination of speed and functionality makes C++
+one of the most widely-used programming languages.
 
 ```c++
-///////////////////////////////////////
+//////////////////
-// C++ differences
+// Comparison to C
-///////////////////////////////////////
+//////////////////
 
+// C++ is _almost_ a superset of C and shares its basic syntax for
+// variable declarations, primitive types, and functions.
+// However, C++ varies in some of the following ways:
 
-//In C++
+// A main() function in C++ should return an int,
-//cannot use void main()
+// though void main() is accepted by most compilers (gcc, clang, etc.)
-int main() { //or int main(int argc, char **argv)
+int main() // or int main(int argc, char** argv)
-    //cannot end with return;
+{
-    return 0;
+    return 0; // Can also end without return statement
-    //Can also end without return statement
 }
 
-//In C++
+// In C++, character literals are one byte.
-/*
-  //This could lead to compiler errors and is discouraged
-  //#if 0 #endif pairs are encouraged instead
-*/
-
-//In C++
-sizeof(10) //Typically 4
 sizeof('c') == 1
 
-//In C
+// In C, character literals are the same size as ints.
-sizeof('c') == sizeof(10) //true chars are passed as ints
+sizeof('c') == sizeof(10)
 
 
-//In C++ strict prototyping
+// C++ has strict prototyping
 void func(); // function which accepts no arguments
 
 // In C
-void func(); //function which may accept arguments
+void func(); // function which may accept any number of arguments
 
+// Use nullptr instead of NULL in C++
+int* ip = nullptr;
 
-//In C++
+// C standard headers are available in C++,
-for(int i = 0; i < 10; i++) {;}
+// but are prefixed with "c" and have no .h suffix.
-//In C must int i must be declared before
+#include <cstdio>
-
-
-//C++ Supports Function overloading
-//Provided each function takes different
-//parameters
-
-void printing(char const *myString)
-{printf("String %s\n",myString);} //Hello
-
-void printing(int myInt)
-{printf("My int is %d",myInt);} //15
 
 int main()
 {
-    printing("Hello");
+    printf("Hello, world!\n");
-    printing(15);
+    return 0;
 }
 
+///////////////////////
+// Function overloading
+///////////////////////
 
+// C++ supports function overloading
+// provided each function takes different parameters.
+
+void print(char const* myString)
+{
+    printf("String %s\n", myString);
+}
+
+void print(int myInt)
+{
+    printf("My int is %d", myInt);
+}
+
+int main()
+{
+    printing("Hello"); // Resolves to void print(const char*)
+    printing(15); // Resolves to void print(int)
+}
+
+/////////////////////////////
+// Default function arguments
+/////////////////////////////
 
-//C++ Default Function Arguments
 void two_ints(int a = 1, int b = 4);
 
 int main()
 {
-    two_ints();            // arguments:  1, 4
+    two_ints();      // a = 1,  b = 4
-    two_ints(20);          // arguments: 20, 4
+    two_ints(20);    // a = 20, b = 4
-    two_ints(20, 5);       // arguments: 20, 5
+    two_ints(20, 5); // a = 20, b = 5
 }
 
 
-//C++ added the nullptr which is different from 0
+/////////////
-int *ip = nullptr;      // OK
+// Namespaces
-int value = nullptr;    // error: value is no pointer
+/////////////
-
-
-///////////////////////////////////////
-// C++ Additions ontop of C
-///////////////////////////////////////
-
-
-///////////////////////////////////////
-// C++ Namespace
-///////////////////////////////////////
-
-//Namespaces allow you to define your own
-//functions and variables for use
-
-// Use '::' to change variable (or function) scope
-// Putting '::' before a function or variable will
-// reference a global scope
-
-// This allows you to make normal c library calls
-// std is for standard library
-using namespace std;
-
-#include <stdio.h>
-
-int counter = 50;                // global variable
-
-int main()
-{
-    for (int counter = 1;        // this refers to the
-    counter < 2;                 // local variable
-    counter++)
-    {
-        printf("Global var %d local var %d\n",
-            ::counter,           // global variable
-            counter);            // local variable
-        // => Global var 50 local var 1
-    }
-}
 
+// Namespaces provide separate scopes for variable, function,
+// and other declarations.
 // Namespaces can be nested
 
-
+namespace First {
-namespace myFirstNameSpace
+    namespace Nested {
+        void foo()
         {
-    namespace myInnerSoul
+            printf("This is First::Nested::foo\n");
-    {
-        cos(int x)
-        {
-            printf("My inner soul was made to program.");
         }
+    } // end namespace Nested
+} // end namespace First
+
+namespace Second {
+    void foo()
+    {
+        printf("This is Second::foo\n")
     }
 }
 
-namespace anotherNameSpace
+void foo()
 {
-    cos(int x) {;} //does nothing
+    printf("This is global foo\n");
 }
 
 int main()
 {
-    //Specify the full path because main is outside of both namespaces.
+    // Assume everything is from the namespace "Second"
-    //Will print out My inner soul was made to program.
+    // unless otherwise specified.
-    myFirstNameSpace::myInnerSoul::cos(60);
+    using namespace Second;
+
+    foo(); // prints "This is Second::foo"
+    First::Nested::foo(); // prints "This is First::Nested::foo"
+    ::foo(); // prints "This is global foo"
 }
 
+///////////////
+// Input/Output
+///////////////
 
-///////////////////////////////////////
+// C++ input and output uses streams
-// C++ Strings
+// cin, cout, and cerr represent stdin, stdout, and stderr.
-///////////////////////////////////////
+// << is the insertion operator and >> is the extraction operator.
 
-//Strings in C++ are Objects and have many functions
+#include <iostream> // Include for I/O streams
-myString = "Hello";
-myOtherString = " World";
-
-myString + myOtherString; // => "Hello World"
-
-myString + ' You'; // => "Hello You"
-
-myString != myOtherString; //True
-
-//An example of a string method
-myString.append(" Dog"); // => "Hello Dog"
-
-
-///////////////////////////////////////
-// C++ Input Output
-///////////////////////////////////////
-
-//C++ input and output streams
-//cin, cout, cerr, << is insertion and >> is extraction operator
-#include <iostream>
 
 using namespace std;
 
 int main()
 {
-
    int myInt;
 
    // Prints to stdout (or terminal/screen)
@@ -195,135 +168,220 @@ int main()
     cerr << "Used for error messages";
 }
 
+//////////
+// Strings
+//////////
 
-///////////////////////////////////////
+// Strings in C++ are objects and have many member functions
-// C++ Classes
+#include <string>
-///////////////////////////////////////
 
+using namespace std; // Strings are in the namespace std (standard library)
+
+string myString = "Hello";
+string myOtherString = " World";
+
+// + is used for concatenation.
+cout << myString + myOtherString; // "Hello World"
+
+cout << myString + " You"; // "Hello You"
+
+// C++ strings are mutable and have value semantics.
+myString.append(" Dog");
+cout << myString; // "Hello Dog"
+
+
+/////////////
+// References
+/////////////
+
+// In addition to pointers like the ones in C,
+// C++ has _references_.
+// These are pointer types that cannot be reassigned once set
+// and cannot be null.
+// They also have the same syntax as the variable itself:
+// No * is needed for dereferencing and
+// & (address of) is not used for assignment.
+
+using namespace std;
+
+string foo = "I am foo";
+string bar = "I am bar";
+
+
+string& fooRef = foo; // This creates a reference to foo.
+fooRef += ". Hi!"; // Modifies foo through the reference
+cout << foo; // Prints "I am foo. Hi!"
+
+fooRef = bar; // Error: references cannot be reassigned.
+
+const string& barRef = bar; // Create a const reference to bar.
+// Like C, const values (and pointers and references) cannot be modified.
+barRef += ". Hi!"; // Error, const references cannot be modified.
+
+//////////////////////////////////////////
+// Classes and object-oriented programming
+//////////////////////////////////////////
 
 // First example of classes
 #include <iostream>
 
-//define a class
+// Declare a class.
-class Doggie
+// Classes are usually declared in header (.h or .hpp) files.
-{
+class Dog {
+    // Member variables and functions are private by default.
     std::string name;
     int weight;
 
-   // These are only the declarations
+// All members following this are public
-   //Can also have private and protected
+// until "private:" or "protected:" is found.
 public:
-       //The public methods (can also include variables)
 
     // Default constructor
-   Doggie();
+    Dog();
+
+    // Member function declarations (implementations to follow)
+    // Note that we use std::string here instead of placing
+    // using namespace std;
+    // above.
+    // Never put a "using namespace" statement in a header.
+    void setName(const std::string& dogsName);
 
-   void setName(std::string dogsName);
     void setWeight(int dogsWeight);
-   void printDog();
 
-   //Can define functions within class declaration too
+    // Functions that do not modify the state of the object
-   void dogBark() {std::cout << "Bark Bark\n"}
+    // should be marked as const.
+    // This allows you to call them if given a const reference to the object.
+    // Also note the functions must be explicitly declared as _virtual_
+    // in order to be overridden in derived classes.
+    // Functions are not virtual by default for performance reasons.
+    virtual void print() const;
 
-   //Destructors are methods that free the allocated space
+    // Functions can also be defined inside the class body.
-   ~doggieDestructor();
+    // Functions defined as such are automatically inlined.
-   //if no destructor compiler defines the trivial destructor
+    void bark() const { std::cout << name << " barks!\n" }
 
-//Classes are similar to structs and must close the } with ;
+    // Along with constructors, C++ provides destructors.
-};
+    // These are called when an object is deleted or falls out of scope.
+    // This enables powerful paradigms such as RAII
+    // (http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization)
+    // Destructors must be virtual to allow classes to be derived from this one.
+    virtual ~Dog();
 
-// This is the implementation of the class methods
+}; // A semicolon must follow the class definition.
-// Also called the definition
+
-void Doggie::Doggie () {
+// Class member functions are usually implemented in .cpp files.
-    std::cout << "A doggie is born. Woof!\n";
+void Dog::Dog()
+{
+    std::cout << "A dog has been constructed\n";
 }
 
-void Doggie::setName (std::string doggie_name) {
+// Objects (such as strings) should be passed by reference
+// if you are modifying them or const reference if you are not.
+void Dog::setName(const std::string& dogsName)
+{
     name = doggie_name;
 }
 
-void Doggie::setWeight (int doggie_weight) {
+void Dog::setWeight(int dogsWeight)
-    weight = doggie_weight;
+{
+    weight = dogsWeight;
 }
 
-void Doggie::printDog () {
+// Notice that "virtual" is only needed in the declaration, not the definition.
-    std::cout << "Dog is " << name << " weighs" << weight << "\n";
+void Dog::print() const
+{
+    std::cout << "Dog is " << name << " and weighs " << weight << "kg\n";
 }
 
-void Doggie::~doggieDestructor () {
+void Dog::~Dog()
-    delete[] name;
+{
-    delete weight;
+    cout << "Goodbye " << name << "\n";
 }
 
 int main() {
-  Doggie deedee; // prints out a doggie is born. Woof!
+    Dog myDog; // prints "A dog has been constructed"
-  deedee.setName ("Barkley");
+    myDog.setName("Barkley");
-  deedee.setWeight(1000000);
+    myDog.setWeight(10);
-  deedee.printDog;
+    myDog.printDog(); // prints "Dog is Barkley and weighs 10 kg"
-  //prints => Dog is Barkley weighs 1000000
     return 0;
-}
+} // prints "Goodbye Barkley"
 
+// Inheritance:
 
-//C++ Class inheritance
+// This class inherits everything public and protected from the Dog class
+class OwnedDog : public Dog {
 
-class German_Sheperd : public Doggie
+    void setOwner(const std::string& dogsOwner)
-{
-   //This class now inherits everything public and protected from Doggie class
 
-   //Good practice to put d_ in front of datatypes in classes
+    // Override the behavior of the print function for all OwnedDogs. See
-   std::string d_type;
+    // http://en.wikipedia.org/wiki/Polymorphism_(computer_science)#Subtyping
+    // for a more general introduction if you are unfamiliar with
+    // subtype polymorphism.
+    // The override keyword is optional but makes sure you are actually
+    // overriding the method in a base class.
+    void print() const override;
 
-   public:
+private:
-      void dogType() {d_type = "German Sheperd";}
+    std::string owner;
 };
 
+// Meanwhile, in the corresponding .cpp file:
 
-
+void OwnedDog::setOwner(const std::string& dogsOwner)
-///////////////////////////////////////
-// C++ Exception Handling
-///////////////////////////////////////
-
-try {
-   throw 12.25;  // throws a double no handler declared
-} catch (int errorNum)
 {
-  std::cout << "I caught an int " << errorNum << "\n";
+    owner = dogsOwner;
-//default catcher
-} catch (...)
-{
-    std::cout << "I got an error. Not sure what but I can pass it up.";
-    throw;
 }
 
+void OwnedDog::print() const
+{
+    Dog::print(); // Call the print function in the base Dog class
+    std::cout << "Dog is owned by " << owner << "\n";
+    // Prints "Dog is <name> and weights <weight>"
+    //        "Dog is owned by <owner>"
+}
 
-///////////////////////////////////////
+//////////////////////////////////////////
-// C++ Operator Overloading
+// Initialization and Operator Overloading
-///////////////////////////////////////
+//////////////////////////////////////////
 
-// In C++ you can overload operators such as +, -, new, etc.
+// In C++ you can overload the behavior of operators such as +, -, *, /, etc.
+// This is done by defining a function which is called
+// whenever the operator is used.
 
 #include <iostream>
 using namespace std;
 
-class Vector {
+class Point {
 public:
-        double x,y;
+    // Member variables can be given default values in this manner.
-        Vector () {};
+    double x = 0;
-        Vector (double a, double b) : x(a), y(b) {}
+    double y = 0;
-        Vector operator + (const CVector&);
+
-        Vector operator += (const CVector&);
+    // Define a default constructor which does nothing
+    // but initialize the Point to the default value (0, 0)
+    Point() { };
+
+    // The following syntax is known as an initialization list
+    // and is the proper way to initialize class member values 
+    Point (double a, double b) :
+        x(a),
+        y(b)
+    { /* Do nothing except initialize the values */ }
+
+    // Overload the + operator.
+    Point operator+(const Point& rhs) const;
+
+    // Overload the += operator
+    Point& operator+=(const Point& rhs);
 };
 
-Vector Vector::operator+ (const Vector& rhs)
+Point Point::operator+(const Point& rhs) const
 {
-    Vector temp;
+    // Create a new point that is the sum of this one and rhs.
-    temp.x = x + rhs.x;
+    return Point(x + rhs.x, y + rhs.y);
-    temp.y = y + rhs.y;
-    return temp;
 }
 
-Vector Vector::operator+= (const Vector& rhs)
+Point& Point::operator+=(const Point& rhs)
 {
     x += rhs.x;
     y += rhs.y;
@@ -331,20 +389,45 @@ Vector Vector::operator+= (const Vector& rhs)
 }
 
 int main () {
-    Vector up (0,1);
+    Point up (0,1);
-    Vector right (1,0);
+    Point right (1,0);
-    Vector result;
+    // This calls the Point + operator
-    // This calls the Vector + operator
+    // Point up calls the + (function) with right as its paramater
-    // Vector up calls the + (function) with right as its paramater
+    Point result = up + right;
-    result = up + right;
+    // Prints "Result is upright (1,1)"
-    // prints out => Result is upright (1,1)
     cout << "Result is upright (" << result.x << ',' << result.y << ")\n";
     return 0;
 }
 
+/////////////////////
+// Exception Handling
+/////////////////////
+
+// The standard library provides a few exception types
+// (see http://en.cppreference.com/w/cpp/error/exception)
+// but any type can be thrown an as exception
+#include <exception>
+
+// All exceptions thrown inside the _try_ block can be caught by subsequent
+// _catch_ handlers.
+try {
+    // Do not allocate exceptions on the heap using _new_.
+    throw std::exception("A problem occurred");
+}
+// Catch exceptions by const reference if they are objects
+catch (const std::exception& ex)
+{
+  std::cout << ex.what();
+// Catches any exception not caught by previous _catch_ blocks
+} catch (...)
+{
+    std::cout << "Unknown exception caught";
+    throw; // Re-throws the exception
+}
 ```
-Futher Reading
+Futher Reading:
 
-for more resources see: http://www.icce.rug.nl/documents/cplusplus/
+An up-to-date language reference can be found at
+<http://cppreference.com/w/cpp>
 
-for other reference material: http://www.cplusplus.com/doc/tutorial/
+Additional resources may be found at <http://cplusplus.com>