计算机专业外文翻译--c 的起源一个小的历史

外文原文The Origins of C++: A Little HistoryComputer technology has evolved at an amazing rate over the past few decades. Today a notebook computer can compute faster and store more information than the mainframe computers of the 1960s. Computer languages have evolved, too. The changes may not be as dramatic, but they are important. Bigger, more powerful computers spawn bigger, more complex programs, which, in turn, raise new problems in program management and maintenance.In the 1970s, languages such as C and Pascal helped usher in an era of structured programming,a philosophy that brought some order and discipline to a field badly in need of these qualities. Besides providing the tools for structured programming, C also produced compact,fast-running programs, along with the ability to address hardware matters, such as managing communication ports and disk drives. These gifts helped make C the dominant programming language in the 1980s. Meanwhile, the 1980s witnessed the growth of a new programming paradigm: object-oriented programming, or OOP, as embodied in languages such as SmallTalk and C++. Let’s examine these C and OOP a bit more closely.The Mechanics of Creating a ProgramSuppose you’ve written a C++ program. How do you get it running? The exact steps depend on your computer environment and the particular C++ compiler you use, but they should resemble the following steps:1. Use a text editor of some sort to write the program and save it in a file. This file constitutes the source code for your program.2. Compile the source code. This means running a program that translates the source code to the internal language, called machine language, used by the host computer. The file containing the translated program is the object code for your program.3. Link the object code with additional code. For example, C++ programs normally use libraries. A C++ library contains object code for a collection of computer routines, called functions, to perform tasks such as displaying information onscreen or calculating the square root of a number. Linking combines your object code with object code for the functions you use and with some standard startup code to produce a runtime version of your program. The file containing this final product is called the executable code.CAsyncSocketA CAsyncSocket object represents a Windows Socket — an endpoint of network communication. Class CAsyncSocket encapsulates the Windows Sockets API, providing an object-oriented abstraction for programmers who want to use Windows Sockets in conjunction with MFC.This class is based on the assumption that you understand network communications. You are responsible for handling blocking, byte-order differences, and conversions between Unicode and multibyte character set (MBCS) strings. If you want a more convenient interface that manages these issues for you, see class CSocket.To use a CAsyncSocket object, call its constructor, then call the Create function to create the underlying socket handle (type SOCKET), except on accepted sockets. For a server socket call the Listen member function, and for a client socket call the Connect member function. The server socket should call the Accept function upon receiving a connection request. Use the remaining CAsyncSocket functions to carry out communications between sockets. Upon completion, destroy the CAsyncSocket object if it was created on the heap; the destructor automatically calls the Close function.CsocketClass CSocket derives from CAsyncSocket and inherits its encapsulation of the Windows Sockets API. A CSocket object represents a higher level of abstraction of the Windows Sockets API than that of a CAsyncSocket object. CSocket works with classes CSocketFile and CArchive to manage the sending and receiving of data.A CSocket object also provides blocking, which is essential to the synchronous operation of CArchive. Blocking functions, such as Receive, Send, ReceiveFrom, SendTo, and Accept (all inherited from CAsyncSocket), do not return a WSAEWOULDBLOCK error in CSocket. Instead, these functions wait until the operation completes. Additionally, the original call will terminate with the error WSAEINTR if CancelBlockingCall is called while one of these functions is blocking.To use a CSocket object, call the constructor, then call Create to create the underlying SOCKET handle (type SOCKET). The default parameters of Create create a stream socket, but if you are not using the socket with a CArchive object, you can specify a parameter to create a datagram socket instead, or bind to a specific port to create a server socket. Connect to a client socket using Connect on the client side and Accept on the server side. Then create a CSocketFile object and associate it to the CSocket object in the CSocketFile constructor. Next, create a CArchive object for sending and one for receiving data (as needed), then associate them with the CSocketFile object in the CArchive constructor. When communications are complete, destroy the CArchive, CSocketFile, and CSocket objects.CSocketFileA CSocketFile object is a CFile object used for sending and receiving data across a network via Windows Sockets. You can attach the CSocketFile object to a CSocket object for this purpose. You also can — and usually do — attach the CSocketFile object to a CArchive object to simplify sending and receiving data using MFC serialization.To serialize (send) data, you insert it into the archive, which calls CSocketFile member functions to write data to the CSocket object. To deserialize (receive) data, you extract from the archive. This causes the archive to call CSocketFile member functions to read data from the CSocket object.Tip Besides using CSocketFile as described here, you can use it as a stand-alone file object, just as you can with CFile, its base class. You can also use CSocketFile with any archive-based MFC serialization functions. Because CSocketFile does not support all of CFile’s functionality, some default MFC serialize functions are not compatible with CSocketFile. This is particularly true of the CEditView class. You should not try to serialize CEditView data through a CArchive object attached to a CSocketFile object using CEditView::SerializeRaw; use CEditView::Serialize instead. The SerializeRaw function expects the file object to have functions, such as Seek, that CSocketFile does not have.Using the MFC Source FilesThe Microsoft Foundation Class Library (MFC) supplies full source code. Header files (.H) are in the MFC\Include directory; implementation files (.Cpp) are in the MFC\Src directory.Note The MFC\Src directory contains a makefile you can use with NMake to build MFC library versions, including a browse version. A browse version of MFC is useful for tracing through the calling structure of MFC itself. The file Readme.Txt in that directory explains how to use this makefile.This family of articles explains the conventions that MFC uses to comment the various parts of each class, what these comments mean, and what you should expect to find in each section. ClassWizard and AppWizard use similar conventions for the classes they create for you, and you will probably find these conventions useful for your own code.You might be familiar with the public, protected, and private C++ keywords. When looking at the MFC header files, you'll find that each class may have several of each of these. For example, public member variables and functions might be under more than one public keyword. This is because MFC separates member variables and functions based on their use, not by the type of access allowed. MFC uses private sparingly — even items considered implementation details are generally protected and many times are public. Although access to the implementation details is discouraged, MFC leaves the decision to you.中文译文c++的起源:一个小的历史过去的几十年计算机技术以惊人的速度得到发展。