Translated "Comparision to C", "Function overloading", "Default arguments" and "Namespaces" sections

1 files changed, 871 insertions, 2 deletions

diff --git a/ru-ru/c++-ru.html.markdown b/ru-ru/c++-ru.html.markdown
index 7fb8b9da..99798bbb 100644
--- a/ru-ru/c++-ru.html.markdown
+++ b/ru-ru/c++-ru.html.markdown
@@ -6,7 +6,6 @@ contributors:
     - ["Matt Kline", "https://github.com/mrkline"]
     - ["Geoff Liu", "http://geoffliu.me"]
     - ["Connor Waters", "http://github.com/connorwaters"]
-	- ["Bohdan Shtepan", "http://modern-dev.com"]
 translators:
     - ["Bohdan Shtepan", "http://modern-dev.com"]
 lang: ru-ru
@@ -25,4 +24,874 @@ C++ - компилируемый, статически типизированн�
 он широко применяется т.к. код написанный на C++ компилируется в набор инструкций, которые могут быть выполнены напрямую
 процессором. C++ широко используется для разработки программного обеспечения, являясь одним из самых популярных языков
 программирования. Область его применения включает создание операционных систем, разнообразных прикладных программ, драйверов
-устройств, приложений для встраиваемых систем, высокопроизводительных серверов, а также развлекательных приложений (игр).
\ No newline at end of file
+устройств, приложений для встраиваемых систем, высокопроизводительных серверов, а также развлекательных приложений (игр).
+
+```c++
+//////////////////
+// Сравнение с C
+//////////////////
+
+// C++ практически представляет собой надмножество C и имеет схожий синтаксис
+// для объявления переменных, примитивов и функций.
+
+// Также как и в С, точкой входа в программу является функция с именем main,
+// которая возвращает целочисленное значение.
+// Это значение является кодом ответа программы.
+// Смотрите https://goo.gl/JYGKyv для более подробной информации.
+int main(int argc, char** argv)
+{
+    // Аргументы командной строки переданные в программу хранятся в переменных
+	// argc и argv, также как и в C.
+    // argc указывает на количество аргументов,
+    // а argv является масивом C-подобных строк (char*), который непосредсвенно
+	// содержит аргументы.
+    // Первым аргументом всегда передается имя программы.
+    // argc и argv могут быть опущены если вы не планируете работать с аругментамы
+	// коммандной строки.
+	// Тогда сигнатура функции будет иметь следующий вид int main()
+
+    // Возвращаемое значение 0 указывает на успешное завершение программы.
+    return 0;
+}
+
+// Тем не менее, C++ имеет свои отличия:
+
+// В C++, символьные литералы являются символами.
+sizeof('c') == sizeof(char) == 1
+
+// В С, символьные литералы - целые числа.
+sizeof('c') == sizeof(int)
+
+
+// C++ имеет строго прототипирование.
+void func(); // функция, которая не принимает аргументов.
+
+// In C
+void func(); // функция, которая может принять сколько угодно аргументов.
+
+// Использование nullptr вместо NULL в C++.
+int* ip = nullptr;
+
+// Стандартные заголовочные файлы С доступны в С++,
+// но с префиксом "с" и не имеют суффикса .h.
+#include <cstdio>
+
+int main()
+{
+    printf("Hello, world!\n");
+    return 0;
+}
+
+///////////////////////
+// Перегрузка функций
+///////////////////////
+
+// С++ поддерживает перегрузку функций, при условии,
+// что каждая функция принимает различные параметры.
+
+void print(char const* myString)
+{
+    printf("String %s\n", myString);
+}
+
+void print(int myInt)
+{
+    printf("My int is %d", myInt);
+}
+
+int main()
+{
+    print("Hello"); // Использование void print(const char*)
+    print(15); // Использование void print(int)
+}
+
+/////////////////////////////
+// Аргументы функций по умолчанию
+/////////////////////////////
+
+// Вы можете предоставить аргументы по умолчанию для функции,
+// если они не предоставлены при вызове функции.
+
+void doSomethingWithInts(int a = 1, int b = 4)
+{
+    // Здесь что-то делаем с числами
+}
+
+int main()
+{
+    doSomethingWithInts();      // a = 1,  b = 4
+    doSomethingWithInts(20);    // a = 20, b = 4
+    doSomethingWithInts(20, 5); // a = 20, b = 5
+}
+
+// Аргументы по умолчанию должен быть в конце списка аргументов.
+
+void invalidDeclaration(int a = 1, int b) // Ошибка!
+{
+}
+
+
+/////////////
+// Пространства имен
+/////////////
+
+// Пространства имен предоставляют отдельные области для переменной,
+// функции и других объявлений.
+// Пространства имен могут быть вложенными.
+
+namespace First {
+    namespace Nested {
+        void foo()
+        {
+            printf("This is First::Nested::foo\n");
+        }
+    } // конец пространства имен Nested
+} // конец пространства имен First
+
+namespace Second {
+    void foo()
+    {
+        printf("This is Second::foo\n")
+    }
+}
+
+void foo()
+{
+    printf("This is global foo\n");
+}
+
+int main()
+{
+    // Включает все функци с пространства имен Second в текущую область видиомти.
+    // Обратите внимание, что простой вызов foo() больше не работает,
+    // так как теперь не ясно вызываем ли мы foo с пространства имен Second или
+	// из глобальной области видимости.
+    using namespace Second;
+
+    Second::foo(); // напечатает "This is Second::foo"
+    First::Nested::foo(); // напечатает "This is First::Nested::foo"
+    ::foo(); // напечатает "This is global foo"
+}
+
+///////////////
+// Ввод/Вывод
+///////////////
+
+// C++ input and output uses streams
+// cin, cout, and cerr represent stdin, stdout, and stderr.
+// << is the insertion operator and >> is the extraction operator.
+
+#include <iostream> // Include for I/O streams
+
+using namespace std; // Streams are in the std namespace (standard library)
+
+int main()
+{
+   int myInt;
+
+   // Prints to stdout (or terminal/screen)
+   cout << "Enter your favorite number:\n";
+   // Takes in input
+   cin >> myInt;
+
+   // cout can also be formatted
+   cout << "Your favorite number is " << myInt << "\n";
+   // prints "Your favorite number is <myInt>"
+
+    cerr << "Used for error messages";
+}
+
+//////////
+// Строки
+//////////
+
+// Strings in C++ are objects and have many member functions
+#include <string>
+
+using namespace std; // Strings are also 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 << fooRef; // Prints "I am foo. Hi!"
+
+// Doesn't reassign "fooRef". This is the same as "foo = bar", and
+//   foo == "I am bar"
+// after this line.
+cout << &fooRef << endl; //Prints the address of foo
+fooRef = bar;
+cout << &fooRef << endl; //Still prints the address of foo
+cout << fooRef;  // Prints "I am bar"
+
+//The address of fooRef remains the same, i.e. it is still referring to foo.
+
+
+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.
+
+// Sidetrack: Before we talk more about references, we must introduce a concept
+// called a temporary object. Suppose we have the following code:
+string tempObjectFun() { ... }
+string retVal = tempObjectFun();
+
+// What happens in the second line is actually:
+//   - a string object is returned from tempObjectFun
+//   - a new string is constructed with the returned object as argument to the
+//     constructor
+//   - the returned object is destroyed
+// The returned object is called a temporary object. Temporary objects are
+// created whenever a function returns an object, and they are destroyed at the
+// end of the evaluation of the enclosing expression (Well, this is what the
+// standard says, but compilers are allowed to change this behavior. Look up
+// "return value optimization" if you're into this kind of details). So in this
+// code:
+foo(bar(tempObjectFun()))
+
+// assuming foo and bar exist, the object returned from tempObjectFun is
+// passed to bar, and it is destroyed before foo is called.
+
+// Now back to references. The exception to the "at the end of the enclosing
+// expression" rule is if a temporary object is bound to a const reference, in
+// which case its life gets extended to the current scope:
+
+void constReferenceTempObjectFun() {
+  // constRef gets the temporary object, and it is valid until the end of this
+  // function.
+  const string& constRef = tempObjectFun();
+  ...
+}
+
+// Another kind of reference introduced in C++11 is specifically for temporary
+// objects. You cannot have a variable of its type, but it takes precedence in
+// overload resolution:
+
+void someFun(string& s) { ... }  // Regular reference
+void someFun(string&& s) { ... }  // Reference to temporary object
+
+string foo;
+someFun(foo);  // Calls the version with regular reference
+someFun(tempObjectFun());  // Calls the version with temporary reference
+
+// For example, you will see these two versions of constructors for
+// std::basic_string:
+basic_string(const basic_string& other);
+basic_string(basic_string&& other);
+
+// Idea being if we are constructing a new string from a temporary object (which
+// is going to be destroyed soon anyway), we can have a more efficient
+// constructor that "salvages" parts of that temporary string. You will see this
+// concept referred to as "move semantics".
+
+/////////////////////
+// Enums
+/////////////////////
+
+// Enums are a way to assign a value to a constant most commonly used for
+// easier visualization and reading of code
+enum ECarTypes
+{
+  Sedan,
+  Hatchback,
+  SUV,
+  Wagon
+};
+
+ECarTypes GetPreferredCarType()
+{
+	return ECarTypes::Hatchback;
+}
+
+// As of C++11 there is an easy way to assign a type to the enum which can be
+// useful in serialization of data and converting enums back-and-forth between 
+// the desired type and their respective constants
+enum ECarTypes : uint8_t
+{
+  Sedan, // 0
+  Hatchback, // 1
+  SUV = 254, // 254
+  Hybrid // 255
+};
+
+void WriteByteToFile(uint8_t InputValue)
+{
+	// Serialize the InputValue to a file
+}
+
+void WritePreferredCarTypeToFile(ECarTypes InputCarType)
+{
+	// The enum is implicitly converted to a uint8_t due to its declared enum type
+	WriteByteToFile(InputCarType);
+}
+
+// On the other hand you may not want enums to be accidentally cast to an integer
+// type or to other enums so it is instead possible to create an enum class which 
+// won't be implicitly converted
+enum class ECarTypes : uint8_t
+{
+  Sedan, // 0
+  Hatchback, // 1
+  SUV = 254, // 254
+  Hybrid // 255
+};
+
+void WriteByteToFile(uint8_t InputValue)
+{
+	// Serialize the InputValue to a file
+}
+
+void WritePreferredCarTypeToFile(ECarTypes InputCarType)
+{
+	// Won't compile even though ECarTypes is a uint8_t due to the enum
+	// being declared as an "enum class"!
+	WriteByteToFile(InputCarType);
+}
+
+//////////////////////////////////////////
+// Classes and object-oriented programming
+//////////////////////////////////////////
+
+// First example of classes
+#include <iostream>
+
+// Declare a class.
+// 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;
+
+// All members following this are public
+// until "private:" or "protected:" is found.
+public:
+
+    // Default constructor
+    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 setWeight(int dogsWeight);
+
+    // Functions that do not modify the state of the object
+    // 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;
+
+    // Functions can also be defined inside the class body.
+    // Functions defined as such are automatically inlined.
+    void bark() const { std::cout << name << " barks!\n"; }
+
+    // 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
+    // (see below)
+    // The destructor should be virtual if a class is to be derived from;
+    // if it is not virtual, then the derived class' destructor will
+    // not be called if the object is destroyed through a base-class reference
+    // or pointer.
+    virtual ~Dog();
+
+}; // A semicolon must follow the class definition.
+
+// Class member functions are usually implemented in .cpp files.
+Dog::Dog()
+{
+    std::cout << "A dog has been constructed\n";
+}
+
+// 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 = dogsName;
+}
+
+void Dog::setWeight(int dogsWeight)
+{
+    weight = dogsWeight;
+}
+
+// Notice that "virtual" is only needed in the declaration, not the definition.
+void Dog::print() const
+{
+    std::cout << "Dog is " << name << " and weighs " << weight << "kg\n";
+}
+
+Dog::~Dog()
+{
+    cout << "Goodbye " << name << "\n";
+}
+
+int main() {
+    Dog myDog; // prints "A dog has been constructed"
+    myDog.setName("Barkley");
+    myDog.setWeight(10);
+    myDog.print(); // prints "Dog is Barkley and weighs 10 kg"
+    return 0;
+} // prints "Goodbye Barkley"
+
+// Inheritance:
+
+// This class inherits everything public and protected from the Dog class
+// as well as private but may not directly access private members/methods 
+// without a public or protected method for doing so
+class OwnedDog : public Dog {
+
+    void setOwner(const std::string& dogsOwner);
+
+    // Override the behavior of the print function for all OwnedDogs. See
+    // 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;
+
+private:
+    std::string owner;
+};
+
+// Meanwhile, in the corresponding .cpp file:
+
+void OwnedDog::setOwner(const std::string& dogsOwner)
+{
+    owner = dogsOwner;
+}
+
+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>"
+}
+
+//////////////////////////////////////////
+// Initialization and Operator Overloading
+//////////////////////////////////////////
+
+// 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 Point {
+public:
+    // Member variables can be given default values in this manner.
+    double x = 0;
+    double y = 0;
+
+    // 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);
+
+    // It would also make sense to add the - and -= operators,
+    // but we will skip those for brevity.
+};
+
+Point Point::operator+(const Point& rhs) const
+{
+    // Create a new point that is the sum of this one and rhs.
+    return Point(x + rhs.x, y + rhs.y);
+}
+
+Point& Point::operator+=(const Point& rhs)
+{
+    x += rhs.x;
+    y += rhs.y;
+    return *this;
+}
+
+int main () {
+    Point up (0,1);
+    Point right (1,0);
+    // This calls the Point + operator
+    // Point up calls the + (function) with right as its parameter
+    Point result = up + right;
+    // Prints "Result is upright (1,1)"
+    cout << "Result is upright (" << result.x << ',' << result.y << ")\n";
+    return 0;
+}
+
+/////////////////////
+// Templates
+/////////////////////
+
+// Templates in C++ are mostly used for generic programming, though they are
+// much more powerful than generic constructs in other languages. They also
+// support explicit and partial specialization and functional-style type
+// classes; in fact, they are a Turing-complete functional language embedded
+// in C++!
+
+// We start with the kind of generic programming you might be familiar with. To
+// define a class or function that takes a type parameter:
+template<class T>
+class Box {
+public:
+    // In this class, T can be used as any other type.
+    void insert(const T&) { ... }
+};
+
+// During compilation, the compiler actually generates copies of each template
+// with parameters substituted, so the full definition of the class must be
+// present at each invocation. This is why you will see template classes defined
+// entirely in header files.
+
+// To instantiate a template class on the stack:
+Box<int> intBox;
+
+// and you can use it as you would expect:
+intBox.insert(123);
+
+// You can, of course, nest templates:
+Box<Box<int> > boxOfBox;
+boxOfBox.insert(intBox);
+
+// Until C++11, you had to place a space between the two '>'s, otherwise '>>'
+// would be parsed as the right shift operator.
+
+// You will sometimes see
+//   template<typename T>
+// instead. The 'class' keyword and 'typename' keywords are _mostly_
+// interchangeable in this case. For the full explanation, see
+//   http://en.wikipedia.org/wiki/Typename
+// (yes, that keyword has its own Wikipedia page).
+
+// Similarly, a template function:
+template<class T>
+void barkThreeTimes(const T& input)
+{
+    input.bark();
+    input.bark();
+    input.bark();
+}
+
+// Notice that nothing is specified about the type parameters here. The compiler
+// will generate and then type-check every invocation of the template, so the
+// above function works with any type 'T' that has a const 'bark' method!
+
+Dog fluffy;
+fluffy.setName("Fluffy")
+barkThreeTimes(fluffy); // Prints "Fluffy barks" three times.
+
+// Template parameters don't have to be classes:
+template<int Y>
+void printMessage() {
+  cout << "Learn C++ in " << Y << " minutes!" << endl;
+}
+
+// And you can explicitly specialize templates for more efficient code. Of
+// course, most real-world uses of specialization are not as trivial as this.
+// Note that you still need to declare the function (or class) as a template
+// even if you explicitly specified all parameters.
+template<>
+void printMessage<10>() {
+  cout << "Learn C++ faster in only 10 minutes!" << endl;
+}
+
+printMessage<20>();  // Prints "Learn C++ in 20 minutes!"
+printMessage<10>();  // Prints "Learn C++ faster in only 10 minutes!"
+
+
+/////////////////////
+// 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>
+#include <stdexcept>
+
+// 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::runtime_error("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
+}
+
+///////
+// RAII
+///////
+
+// RAII stands for "Resource Acquisition Is Initialization".
+// It is often considered the most powerful paradigm in C++
+// and is the simple concept that a constructor for an object
+// acquires that object's resources and the destructor releases them.
+
+// To understand how this is useful,
+// consider a function that uses a C file handle:
+void doSomethingWithAFile(const char* filename)
+{
+    // To begin with, assume nothing can fail.
+
+    FILE* fh = fopen(filename, "r"); // Open the file in read mode.
+
+    doSomethingWithTheFile(fh);
+    doSomethingElseWithIt(fh);
+
+    fclose(fh); // Close the file handle.
+}
+
+// Unfortunately, things are quickly complicated by error handling.
+// Suppose fopen can fail, and that doSomethingWithTheFile and
+// doSomethingElseWithIt return error codes if they fail.
+//  (Exceptions are the preferred way of handling failure,
+//   but some programmers, especially those with a C background,
+//   disagree on the utility of exceptions).
+// We now have to check each call for failure and close the file handle
+// if a problem occurred.
+bool doSomethingWithAFile(const char* filename)
+{
+    FILE* fh = fopen(filename, "r"); // Open the file in read mode
+    if (fh == nullptr) // The returned pointer is null on failure.
+        return false; // Report that failure to the caller.
+
+    // Assume each function returns false if it failed
+    if (!doSomethingWithTheFile(fh)) {
+        fclose(fh); // Close the file handle so it doesn't leak.
+        return false; // Propagate the error.
+    }
+    if (!doSomethingElseWithIt(fh)) {
+        fclose(fh); // Close the file handle so it doesn't leak.
+        return false; // Propagate the error.
+    }
+
+    fclose(fh); // Close the file handle so it doesn't leak.
+    return true; // Indicate success
+}
+
+// C programmers often clean this up a little bit using goto:
+bool doSomethingWithAFile(const char* filename)
+{
+    FILE* fh = fopen(filename, "r");
+    if (fh == nullptr)
+        return false;
+
+    if (!doSomethingWithTheFile(fh))
+        goto failure;
+
+    if (!doSomethingElseWithIt(fh))
+        goto failure;
+
+    fclose(fh); // Close the file
+    return true; // Indicate success
+
+failure:
+    fclose(fh);
+    return false; // Propagate the error
+}
+
+// If the functions indicate errors using exceptions,
+// things are a little cleaner, but still sub-optimal.
+void doSomethingWithAFile(const char* filename)
+{
+    FILE* fh = fopen(filename, "r"); // Open the file in read mode
+    if (fh == nullptr)
+        throw std::runtime_error("Could not open the file.");
+
+    try {
+        doSomethingWithTheFile(fh);
+        doSomethingElseWithIt(fh);
+    }
+    catch (...) {
+        fclose(fh); // Be sure to close the file if an error occurs.
+        throw; // Then re-throw the exception.
+    }
+
+    fclose(fh); // Close the file
+    // Everything succeeded
+}
+
+// Compare this to the use of C++'s file stream class (fstream)
+// fstream uses its destructor to close the file.
+// Recall from above that destructors are automatically called
+// whenever an object falls out of scope.
+void doSomethingWithAFile(const std::string& filename)
+{
+    // ifstream is short for input file stream
+    std::ifstream fh(filename); // Open the file
+
+    // Do things with the file
+    doSomethingWithTheFile(fh);
+    doSomethingElseWithIt(fh);
+
+} // The file is automatically closed here by the destructor
+
+// This has _massive_ advantages:
+// 1. No matter what happens,
+//    the resource (in this case the file handle) will be cleaned up.
+//    Once you write the destructor correctly,
+//    It is _impossible_ to forget to close the handle and leak the resource.
+// 2. Note that the code is much cleaner.
+//    The destructor handles closing the file behind the scenes
+//    without you having to worry about it.
+// 3. The code is exception safe.
+//    An exception can be thrown anywhere in the function and cleanup
+//    will still occur.
+
+// All idiomatic C++ code uses RAII extensively for all resources.
+// Additional examples include
+// - Memory using unique_ptr and shared_ptr
+// - Containers - the standard library linked list,
+//   vector (i.e. self-resizing array), hash maps, and so on
+//   all automatically destroy their contents when they fall out of scope.
+// - Mutexes using lock_guard and unique_lock
+
+// containers with object keys of non-primitive values (custom classes) require
+// compare function in the object itself or as a function pointer. Primitives
+// have default comparators, but you can override it.
+class Foo {
+public:
+	int j;
+	Foo(int a) : j(a) {}
+};
+struct compareFunction {
+    bool operator()(const Foo& a, const Foo& b) const {
+        return a.j < b.j;
+    }
+};
+//this isn't allowed (although it can vary depending on compiler)
+//std::map<Foo, int> fooMap;
+std::map<Foo, int, compareFunction> fooMap;
+fooMap[Foo(1)]  = 1;
+fooMap.find(Foo(1)); //true
+
+/////////////////////
+// Fun stuff
+/////////////////////
+
+// Aspects of C++ that may be surprising to newcomers (and even some veterans).
+// This section is, unfortunately, wildly incomplete; C++ is one of the easiest
+// languages with which to shoot yourself in the foot.
+
+// You can override private methods!
+class Foo {
+  virtual void bar();
+};
+class FooSub : public Foo {
+  virtual void bar();  // Overrides Foo::bar!
+};
+
+
+// 0 == false == NULL (most of the time)!
+bool* pt = new bool;
+*pt = 0; // Sets the value points by 'pt' to false.
+pt = 0;  // Sets 'pt' to the null pointer. Both lines compile without warnings.
+
+// nullptr is supposed to fix some of that issue:
+int* pt2 = new int;
+*pt2 = nullptr; // Doesn't compile
+pt2 = nullptr;  // Sets pt2 to null.
+
+// There is an exception made for bools.
+// This is to allow you to test for null pointers with if(!ptr),
+// but as a consequence you can assign nullptr to a bool directly!
+*pt = nullptr;  // This still compiles, even though '*pt' is a bool!
+
+
+// '=' != '=' != '='!
+// Calls Foo::Foo(const Foo&) or some variant (see move semantics) copy
+// constructor.
+Foo f2;
+Foo f1 = f2;
+
+// Calls Foo::Foo(const Foo&) or variant, but only copies the 'Foo' part of
+// 'fooSub'. Any extra members of 'fooSub' are discarded. This sometimes
+// horrifying behavior is called "object slicing."
+FooSub fooSub;
+Foo f1 = fooSub;
+
+// Calls Foo::operator=(Foo&) or variant.
+Foo f1;
+f1 = f2;
+
+
+// How to truly clear a container:
+class Foo { ... };
+vector<Foo> v;
+for (int i = 0; i < 10; ++i)
+  v.push_back(Foo());
+
+// Following line sets size of v to 0, but destructors don't get called
+// and resources aren't released!
+v.empty();
+v.push_back(Foo());  // New value is copied into the first Foo we inserted
+
+// Truly destroys all values in v. See section about temporary objects for
+// explanation of why this works.
+v.swap(vector<Foo>());
+
+```
+Further Reading:
+
+An up-to-date language reference can be found at
+<http://cppreference.com/w/cpp>
+
+Additional resources may be found at <http://cplusplus.com>