*.cpp:

C++ source code, what you as the programmer write.

*.h:

C++ headers/includes, put class declarations in here. #include'd into other C++ files via the preprocessor.

*.o:

Compiled object file: produced by the compiler for each compilation unit. Generally each *.cpp file produces one *.o file.

*.exe:

Executable: produced by linker, combines all *.o files and any needed libraries into one program that you can run.

private

only methods in this class can access

protected

also subclasses can access

public

anyone can access

  	#include <iostream>
	using namespace std;
	int main() {
		int choice;
		cout << "Do you like pie? [1 for yes, 0 for no] ";
		cin >> choice;
		switch (choice) {
			case 1: cout << "Me too!" << endl; break;
			case 0: cout << "Sorry!" << endl; break;
			default: cout << "Please enter 0 or 1" << endl;
		}
	}

persistent storage:

a local variable inside a function that is declared static preserves its value across calls to that function. If an initial value is given, that initialization is done only once.

file scope:

global variables marked static are limited in scope to only that file; otherwise, they are accessible everywhere in the program.

class member:

attributes/methods of a class which are marked static belong to the class as a whole, rather than to individual instances of that class. Class methods may only reference other class methods or class attributes.

	#include 
	class Gadget {
	private:
		int secret;
	public:
		Gadget(int s=0) : secret(s) {
			std::cout << "Creating a Gadget with secret=" 
				<< secret << std::endl;
		}
		~Gadget() {
			std::cout << "Destroying a Gadget (secret=" 
				<< secret << ")" << std::endl;
		}
	}

	class Person {
		void dealWithStress() = 0;
	}
	class Woman : Person {
		void dealWithStress() { talkWithGirlfriends(); }
	}
	class Man : Person {
		void dealWithStress() { playGames(); }
	}

Application:

top-most layer, interfaces with the program. HTTP, SMTP (email), etc.

Presentation:

complex data representation, encryption. SSL.

Session:

authentication, suspend/resume session (save/restore state). SSH, sockets.

Transport:

setup of connection, guarantees of reliability. TCP, UDP.

Network:

addressing and routing on the Internet. IP.

Data link:

addressing the network interface, MAC addresses. Ethernet.

Physical:

physical medium of sending signals: photos, electrons. Cat5 cables, Fiber optics, wireless radio.

NAT:

network address translation. Local network sends all traffic through a gateway. Only the gateway gets a real public IPv4 address. All local interfaces get private IPv4 addresses (e.g., within the block 192.168.* or 10.*). Connections get mapped to ports on the gateway machine.

IPv6:

new revision of IP uses 128-bit addresses: not likely to run out! Last 64 bits use the hardware MAC address of the network interface and so should be globally unique, no matter which network the machine is plugged into.

Server: socket():

Creates a new socket object; akin to buying a phone.

bind():

Connects socket to a port for it to listen on; akin to getting a phone number.

listen():

Enables socket for listening and sets incoming connection queue length; akin to setting call-waiting.

accept():

Blocks (waits) for a client to connect, and returns "Caller ID" info on connecting client. Akin to waiting for someone to call.

send/recv():

Communicate with client.

shutdown():

disable sending and/or receiving; akin to mute.

close():

Hangs up and closes socket.

Client: socket():

Creates a new socket object; akin to buying a phone.

connect():

Tries to connect to specified server on specified port; akin to dialing the phone.

send/recv():

Communicate with server.

shutdown():

disable sending and/or receiving; akin to mute.

close():

Hangs up and closes socket.