What are the characteristics of VB?

Article search: name full-text article home page IT information development language software development WEB development examination authentication database program life programming college e-book hot topic programming forum computer paper C language -C++-C#- NET-JAVA-v B- DELPHI- assembly-data structure

Your current position is: home page-development language -VB programming -VB foundation-browsing articles.

Characteristics of VB

Click: 1078 release date: 2007-9-17-21:59: 55 to enter the forum.

Visual Basic is favored by programming enthusiasts and professional programmers because it has the following characteristics:

1. object-oriented

VB adopts the idea of object-oriented programming. Its basic idea is to decompose complex programming problems into relatively simple sets of objects that can complete independent functions. The so-called "objects" are operational entities, such as forms, command buttons, labels, text boxes in forms, etc. Object-oriented programming is like building blocks. Programmers can directly "draw" different types of objects such as windows, menus and buttons on the screen according to the requirements of program and interface design, and set properties for each object.

2. Event-driven

In the Windows environment, programs run in an event-driven manner. Each object can respond to many different events, and each event can drive a piece of code-event process, which determines the function of the object. This mechanism is often called event-driven. Events can be triggered by user operations or by systems or applications. For example, clicking a command button will trigger the click event of the button, and the code in the event will be executed. If the user does nothing (no event is triggered), the program is in a waiting state. The whole application consists of an independent event flow.

3. Software integrated development

VB provides an integrated development environment for programming. In this environment, programmers can design interfaces, write codes and debug programs until the application is compiled into an executable file that can run in Windows, and an installer is generated for it. The integrated development environment of VB provides great convenience for programmers.

4. Structured programming language

VB has rich data types, which is a language that conforms to the idea of structured programming and is easy to learn. In addition, as a programming language, VB has many unique functions.

5. Powerful database access function

VB can use data controls to access various databases. ADO control provided by VB 6. O can not only realize database operation and control with the least code, but also replace data control and RDO control.

6. Support object linking and embedding technology.

The core of VB is supporting object linking and embedding (OLE) technology, which is a method to access all objects. Using OLE technology, we can develop programs that integrate sound, images, animation, word processing, Web and other objects.

7. Network function

Vb6.o provides DltTML(Dynamic}tTML) design tool. Using this technology, web pages can be created and edited dynamically, and users can develop multifunctional network application software in VB.

8. Multiple application wizards

VB provides various wizards such as application wizard, installation wizard, data object wizard, data form wizard, etc. Through these wizards, you can quickly create different types of applications with different functions.

9. Support dynamic exchange and dynamic link technology.

Through dynamic data exchange (DDE) programming technology, applications developed by VB can establish data communication with other Windows applications. Through the technology of dynamic link library, functions written in C language or assembly language can be easily called in VB programs, and functions of application program interface (... API) can also be called.

Look. Online help function

In VB, with the help menu and function key F 1, users can easily get the needed help information at any time. The VB help window shows the relevant sample codes, and a large number of sample codes can be obtained by copying and pasting, which provides convenience for users to learn and use.

Visualbasic language

Visual Basic(VB) is an event-driven programming language developed by Microsoft, which includes an auxiliary development environment. By any standard, VB is the most widely used language in the world-not only the developers who praise VB, but also the developers who complain about VB. It comes from the BASIC programming language. VB has a graphical user interface (GUI) and a rapid application development (RAD) system, so it can easily connect to a database or create ActiveX controls using DAO, RDO and ADO. Programmers can easily use the groups provided by VB to quickly build an application.

Development history

199 1 year, Microsoft released Visual Basic 1.0 version. This caused a great sensation at that time. Many experts believe that the emergence of VB is an epoch-making event in the history of software development. Actually, from our current point of view, does the function of VB 1.0 really exist? It is too weak; (But recently VB 6.0, VB. NET function is still quite big! )。 But at that time, Yan was the first "visual" programming software. This makes programmers enjoy it and try to create software on the platform of VB. Microsoft also lost no time in launching three versions of VB2.0, VB3.0 and VB 4.0? Moreover, since VB3, Microsoft has integrated the database driver of ACCESS into VB, making VB's database programming? The strength has been greatly improved. Since VB4, VB has also introduced the idea of object-oriented programming. VB is powerful @ easy to learn. Moreover, VB also introduced "controls"? Concept, so that a lot of VB programs have been compiled? Directly used by us. In 2002. NET 2002 (v7.0) came out, in 2003, Visual Basic. NET 2003 (v7. 1), and in 2005, Visual Basic 2005 (v8.0) came out. At the same time, a free simplified version of Visual Basic 2005 and an accelerated version of Visual Basic 2005 are introduced for beginners and students of Visual Basic. Visual Basic 2005 Express Edition is free, but Microsoft is a listed company. People who need to use this version must go to Microsoft? Can you register our website and get the product registration code before doing it? Otherwise, Visual Basic 2005 Express Edition will only run for 30 days. The obvious advantage of VB2005 is that you can directly write XP-style buttons. And other controls. But its writing is small? The sequence occupies nearly 10MB of memory. Through years of hair. It has become a special development language. Conditions. Users can quickly create Windows programs with Visual Basic, and now they can write enterprise-level client/server programs and powerful database applications.

A language derived from VB

Microsoft has developed a series of scripting languages about VB?

-VBA VBA, which is included in Microsoft applications (such as Microsoft Office) and third-party products (such as WordPerfect Office). VBA is embedded in various applications, which seems contradictory, but its function is as powerful as VB.

-VBscript is the default ASP language and can also be used for Windows scripts and web page coding. Although its grammar is similar to VB, it is a completely different language. VBS does not make VB runtime run, but is executed by Windows script host. The difference between these two languages reflects the performance of ASP website. When is Microsoft going to develop one? When programming tools, the first decision is profit? Is the most sought-after VB6 old-fashioned, or just heavy? Establish new tools for engineering development. Microsoft later developed it? The successor of VB, Visual Basic. NET, too. NET platform. VB.net programming language is an object-oriented programming language, which is not completely compatible with VB.

language feature

The central idea of VB is to make programmers simple, whether novice or expert. Using VB, the GUI system of application program can be established simply, but it can also develop quite complicated programs. VB program is a combination of visual components based on forms, which adds? Code that specifies the generated properties and methods. Because the nature and methods of tacit understanding have been partially defined in the software, programmers can complete a simple program without writing too much code. In the past, the performance problems of VB programs were always put on the desktop, but with the rapid improvement of computer speed, the debate about performance has become less and less. The addition and change of form controls are realized by drag-and-drop technology. A toolbox full of controls to display available controls (such as text boxes or buttons). Each control has its own properties and events. The default property value will be provided when the control is created, but the programmer can also change it. The attribute value can be changed with the user's actions and modifications at runtime, thus forming a "one size fits all". Dynamic program. For example, code that can change the position of a control is added to a small change event of a form. Whenever the user changes the window size at run time, the control will also change its position. By adding the corresponding code in the text change event in the text box, the program can automatically interpret or block the input of certain characters when inputting text. The journey of VB? Can contain one or more forms, or. A main form and multiple subforms, similar to the appearance of the operating system. Dialog windows with few functions (such as forms without maximize and minimize buttons) can be used to provide pop-up functions? Can VB components have a user interface, or? No. In this way, the server-side program can handle the added module. VB uses the method of parameter calculation to collect garbage, which contains a large number of objects and provides basic object-oriented support. Because more and more organizations appear, engineers can choose their own extension libraries. Really? Different languages, VB is case-insensitive, but mapping can automatically convert keywords into standard case, forcing the entities at the entrance of the symbol table to follow the writing rules. By default, string comparisons are case sensitive, but this feature can be turned off. VB has made many external controls? Have your own living space. Provides a large number of third-party components for VB. VB also provides the establishment, use? Reuse the methods of these controls, but because of the language? Question, create another merge from one application? Simple.

school term

When discussing Visual Basic, you often hear the following terms @, so it is very helpful to have a basic understanding of these terms.

control

Simply put, controls are graphical tools used to form or build Visual Basic applications, including windows, buttons, check boxes, list boxes and data controls? Table controls, picture controls, etc.

event

Actions triggered by the user or the operating system. Events? Such as keystroke, mouse click, double mouse click, time limit or receiving data from the terminal.

way

What does the program code embedded in the object definition determine? How objects process information and respond to events. For example? , the database object has an open recordset and is downloaded from? What is the basis of the method and program for moving one record to another? Element that contains attributes that define its characteristics. What is its task, and who is the party to the event it can respond to? . Controls and forms are examples of all objects in Visual Basic.

target

Controls, tables, etc. Kind of a couple, right? .

process

A code segment written to accomplish certain tasks, and procedures are usually used to respond to certain events. It can be used as a user-defined function of an application.

attribute

What are the properties of the objects that make up the user interface? Specific description. Such as the "object" mentioned above? Size, location, color, width, height, etc. A property called a control. Attributes determine the appearance and sometimes the behavior of an object. Most object attributes are predefined in VB. However, some properties need to be defined during application. Property can provide data for the object @ and retrieve information from the object.

Controversy about VB

opposition

VB is a controversial language: many programmers have strong feelings about the quality of VB programs. Enough people think that VB is not worth their use, and that it is a kind of? The language of children and programmers novice. Since it was founded? It was a simple language from the beginning. Some features in C++ and Java do not appear in VB. While feeling the convenience and speed of post, some functions similar to compile-time type and declaration checking are turned off by default. While lamenting the usability of VB, some programmers generally look at an error similar to "undefined type" in dismay. ? Some critics think that the simple features of VB will make it harmful in the future. Many people have taught themselves VB, but they should not have learned good programming habits. When does VB enter the class? Students won't learn a lot of basic knowledge? Sequence technology and structure, because many technologies are packaged? Among those components that are visible to users. No? Learn standard programming habits, because VB has confusing characteristics, which leads to some inexplicable codes. Moreover, many errors and warnings are turned off by default, and programmers find hidden errors very quickly. Experienced programmers will turn on these options when programming in VB. ? Many critics criticized Microsoft for simply copying the idea of BASIC into VB. Edsger Dijkstra, a famous computer scientist, famously said, "If a student has studied BASIC at the earliest, it is almost impossible for him to learn it? Good programming: because these people have given up? Pan's hope. 1"(Dijkstra has no mercy on Fortran, PL/ 1, COBOL and APL. What's another joke? "Real programmers don't need BASIC. 12 or less? Just use it. "

-It's not that simple. The program it develops can only run in Microsoft Windows.

-It's too big. Visual Studio needs several disks to install. VB programs also need a runtime with the size of 1.4M when they leave the factory.

There is an error in the IDE.

-VB can't integrate the basic API of Windows well, so it is very difficult to program with low-level operation. The low-level memory operation of C language is much simpler than VB.

supporter

However, many supporters of VB explain that the ease of use of VB is its greatest advantage, and it can be used by experienced VB programmers or people who have just learned a little? Develop programs quickly in your own way. In addition, VB programs can connect to the database very simply. For example, controls can be used to bind databases? In this way, the program written in VB can master all the information of the database without writing a line of code. ? Multilingual features such as GoSub, On Error and using the last character of variable names to determine the declaration type (such as string str$) are all grammars from v. VB and most languages, aren't they? This may confuse new programmers. Like sound? "Dim a, b, c As Integer" declares that c is an integer variable, but a, b? It's a variant type. There are some characteristics, than? When a line of code is divided into multiple lines, the underscore character "_" is used. Some programmers use it because it is not standardized and leads to errors.

abstract

VB will attract more praise and criticism, and will continue to be used by users and programmers. It is very suitable for developing user-friendly programs (compared with terminal data), but not suitable for developing other programs (such as joint computing programs).

Features that VB doesn't have

-Legacy. Both VB5 and VB6 are object-oriented programming languages. Yes, it does not contain inheritance features. VB provides special functions, but it still can't meet the needs of programmers. Visual Basic。 NET contains all the object-oriented features.

-Multi-threading support

-Exception handling. Try-Catch-Finally was used against Zhang Chang in VB.net. In VB, there is only the statement "Go to line when an error occurs".

-Support for pointers is very limited.

-VB can only support 8-32-bit plastic surgery, and many languages support it infinitely.

-VB does not allow constant changes in any array. VB does not support the above functions, and programmers need self-reported construction methods to realize similar functions.

VB revolution

VB 1.0 is published in 199 1. This progress in connecting programming languages and user interfaces is called Tripod (sometimes called Ruby)? The original design was completed by Alan Cooper.

time line

-1991April, released by Visual Basic1.0 for Windows.

-1992 September, Visual Basic 1.0 DOS version was released.

-19921/month, released by VB2.0. The reliability and speed of the previous version have been improved.

-/kloc-0 released VB3.0 in the summer of 993, which is divided into standard version and professional version. It contains a data engine, which can directly interpret the Access database.

-1995 In August, VB4.0 released a 32-bit version and a 16-bit version. It includes support for classes.

-1997 February, released by VB5.0. Programmers can use the 32-bit version? Enter the 4.0 version of the 16-bit program, which can be easily compiled. It also includes self-control of users? Support.

-1998 summer, released by VB6.0.

-200 1, by visual Basic.net and. NET framework. Because it uses new cores and functions? So many VB programmers have to rewrite their programs.

-2003, Visual Basic.net 2003 and. NET framework 1. 1 release.

-In 2004, Microsoft opened the beta version of Visual Studio. NET 2005 (code name Whidbey). That contains the beta version. Network framework 2.0

-In 2005, Microsoft announced that it no longer supported Africa. VB online edition. The VB community immediately responded to Guan Zhong's news, and some old users also submitted petitions hoping to continue to provide technical support for VB. Micro? They are unwilling to change their decision at present.

-Visual Studio.net 2005 will be released on June 7th, 2005.

Overview: The next version of Microsoft Visual Basic has three major improvements: Web Forms, Web Services and Object-Oriented Grammar. Web forms enable experienced Visual Basic users to develop network applications as simply as writing independent programs now. Through the SOAP interface, Web services allow you to configure your designed components anywhere you can connect to the Internet. In addition, several key improvements of object-oriented language make Visual Basic code as flexible as C++, including inheritance, polymorphism and overloading. In this regard, you can refer to Steve Ballmer's "VB its keynote on the next generation of visual basic".

Visual Basic has undergone many improvements. However, I have always liked it since its birth: at its core, you can still write your program as in 199 1 year. Of course, compared with that time, its software package has been greatly enhanced, but these improvements are generally complementary, and the purpose of being a programming tool itself is not vague. The purpose of this is to make Visual Basic design, write and debug excellent object-oriented applications more easily and quickly.

The currently used version of Visual Basic 6.0 introduces WebClasses as a simplified method to configure robust network-oriented applications. In fact, WebClasses provides a large number of methods to transplant programs to the network through common tools. (For a detailed discussion on the extensibility of Visual Basic 6.0 under the network, please refer to Ted Pattison's "Advanced Basic Knowledge Column" (Microsoft Internet Developer1published in October 1999).

Recently, I learned that the next version of Visual Basic plans to make some new improvements. The main improvement is that in terms of storage capacity, the storage capacity available to developers has tripled. The next version of Visual Basic plans to adopt a function called Web Forms in the Visual Studio environment. Web Forms represents a brand-new component-based network solution. Web service will become a new XML-based solution, which publishes the event handling function of the middle layer through standard network protocols. At the same time, Visual Basic language will contain some structures that developers have been demanding for a long time, which makes Visual Basic conform to the familiar object-oriented programming habits of C++ and Java users. These improvements will be announced in the next beta version of Visual Basic.

The changes in the next version of Visual Basic are amazing. If you want to get the benefits they bring, use them. If you don't want to, you can use what you are still using. However, it is beneficial to know that the functions realized by C++ and Java can also be realized by a language like Visual Basic, which is much easier to use than C++ and Java.

Future development trend

What impression did this preview give you? This question is good, but you can find the answer. In the past year, we can clearly see the changes in ASP development. These development programs are often composed of some easy-to-read ASP scripts, and the whole program runs on the basis of these scripts. Because ASP interprets and executes the whole script code, people gradually discover the inherent limitations of this technology when assembling various components. I hear more and more developers say that they want to completely separate the event handling function from the script code and put it into a faster compilation model. These models are all written in c++ or Visual Basic and assembled through COM interface.

Visual Basic can satisfy all the reasons you can think of. Designing components with Visual Basic is actually better than using VBScript or JScript? How hard it is. You can write code that is faster and can easily meet your needs. After the release of the next version of Visual Basic, you can use Visual Basic to generate network-oriented objects, which are compatible with ASP. In a word, taking the route of component combination will be considered as the best choice now and in the future.

As I mentioned earlier, Internet-oriented applications written in Visual Basic (and WebClasses) have a broad foundation. The problem is that most WebClasses-based applications are poorly designed. They don't distinguish the different levels of the application well, and confuse the process of the middle layer with the user interface based on DHTML.

The next version of Visual Basic will introduce WebClasses, a carefully selected network development tool. Because it is more extensible, more powerful and truly language-independent. It applies to all tools of Visual Studio. If you pay attention to some basic rules of multi-tier development, you can easily complete this transformation. Pay special attention to separating the middle layer process from the display layer process. It is strongly recommended to refer to Windows when performing these tasks. The architecture of DNA 2000. The core event handling functions must be completed in the middle layer, and you can use various components written in your favorite compilation language to realize these functions. Then, assemble these components into an ASP script file so that they can work together. It would be ideal if most logical operations were placed in event objects instead of scripts. This is not only a good idea to transition to Web services in the future, but also a practice worthy of emulation.