Advanced programming languages

The primary stage of a high-level language is actually from a low-level language(Machine languages and Assembly language)transition to a high-level language, its representative is the first high-level languageFortranlanguage, the problem in the early high-level language is expression processing, whichFortranmeaning of the name(FORmula transformation language)can seeFortran,Basiclanguage introduces the concepts of variables, expressions, statements, etc., because the focus of computer application at that time is numerical calculation, so it is the main difference with the low-level language is also reflected in the automatic processing of expression calculation, and the expression of the calculation further introduced to the control of repeated statements and array subscript, more reflect the"Advanced"the characteristics of the programming. Early high-level languages already have the concept of subroutines, but it should be said that they are only"Sprout"functions and procedures of the State, the functions and processes in the language are the most important facilities in the design stage of the structure program. In the second stage, we call the structural program design phase, the main feature of the structure programming language is two points, one is clear data type description and check, the other is the process and function as the main form of hierarchical programming method. It emphasizes the structure of the program itself. Its representative language first when pushedPascallanguage.

With the high-level language, there is a large number of large-scale programming needs, in which the high-level language of the compilation system itself is a large-scale program. Faced with the design of large programs, the primary stage of high-level language and programming methods are not adapted to, so, the end of the " software crisis " appeared , by Digkstra The "Goto statement harmful " discussion led to Pascal,C and other language and software engineering ideas and structural programming methods. Most of the contemporary programmers are under the guidance of this theory , and create the software industry today so brilliant development of the situation. It can be said that the structure programming language and its design methodology are the inevitable and logical results of the development of high-level language in the early stage.

In this period, it can be said that from the beginning, there are some primitive ideas of the development of the downward stage. For example, inCand thePascalin LanguageThat allows a function or procedure to be treated as a parameter of a function or procedure like data. andALGOL68,Simula67,Modula-2and other languages also set the class(Class)or a similar grammatical component. In data and Functions(Process)between the modules formed by the"move into table","move out of a table"to specify the invocation relationship between each other. In theKanth,Aho,Hopcroft,Ullmandata structures and algorithms in the literature ., explicitly pointing out the concept of abstract data types, which areOOPprimitive ideas. Object-Oriented Programming(OOP)as the third stage of the main feature, which can be considered as the maturity of the development of programming methodology, the first object-oriented language is recognized asSmalltalk. In class(Class)and Objects(object)as the main grammatical component, from the idea of abstract data types, the data and code as a whole package, as the object of the physical existence and its function of the formation of a unity, such objects between the inheritance and behavior description of polymorphism, constitutes aOOPthe basic characteristics. Currently, object-oriented design technology has entered the actual development environment of software industry from the research field of methodology, which is not only a kind of occult theory, but also a technique that programmers must master.

Although, Smalltalkwas first accepted by people, some reports suggest that the language has been mastered and used by many users, but the actual situation is that it can replaceClanguage, and can become the main software development language is onlyC + +. It is not new to realize the upgrading of language in an improved way. The concept of data type and the function of process function are strengthened.Fortran,Basicsome new versions of: With classes and objects.Pascallanguage(asTurbo Pascal 5.5, 6.0version)and so on are the new results developed in this way. But withC + +language comparison, is not a success.

C++why become the mainstream language object-oriented programming technology perfect, which means that software development technology matures, on the other hand, the development of software technology today, OOPfor it has not been dispensable, used to add flowers on the improvement measures, but the only way to have no other choice. Compared with early, today's software industry can be said to be different, this difference is not only reflected in the number of software products, varieties, size and function of the complexity of the structure, but also reflected in the SOFTWARE product itself intrinsic characteristics, the concept of program design has gradually undergone an essential change, This change makes the process-oriented structured design approach no longer applicable. For example, most software products(includes system software and application software)It's all event-driven., programmers cannot control the order in which events occur, in other words, the concept of programmer programming has changed. Today's programming goals are not simply understood to tell the machine what to do first, and then what to do, a software development work, in fact, for programmers to choose or design a number of functional modules of the assembly. The so-called assembly, the main is to specify the inter-module message transmission relationship, the function of the so-called module, is the program module receiving, processing and sending messages characteristics. ObviouslyOOPmethod can be said to be the only applicable technology. on the other, modern software has many new features, such as window, dialog box, scroll bar and other graphical user interfaces, because of the complexity of the problem and the convenience of the user interface, and the automatic memory management, dynamic connection of modules, dynamic data exchange and so on, have to be used by a reusable module in the way of programmers. The traditional form of library standard functions does not solve the problem because objects such as windows, dialogs, etc., are not possible with standard(with Parameters)the form of a function to describe, classes and objects are the only appropriate form, and the pastClanguage-rich and powerful library functions are an important reason why they are welcomed by program developers., now, C + +language is based on its standard class library(asBorlandCompany'sWOLand theMicrosoftCompany'sMFCLibrary)as one of the means of defeating other object-oriented languages.

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Advanced programming languages