Where is the most comprehensive and detailed VB programming tutorial?

Visual Basic (VB) Introduction 2007-02-13 19:38Visual Basic (VB) is an event-driven programming language developed by Microsoft that includes an assisted development environment. By any measure, VB is the most spoken language in the world—not just in terms of the number of developers who praise VB but also the number of developers who complain about VB. It is derived from the BASIC programming language. VB has a graphical user interface (GUI) and a rapid application development (RAD) system. You can easily use DAO, RDO, and ADO to connect to the database, or easily create ActiveX controls. Programmers can easily use the components provided by VB to quickly build an application.

Development History

In 1991, Microsoft launched Visual Basic version 1.0. This caused quite a stir at the time. This advancement in connecting programming languages ??and user interfaces was called Tripod (sometimes called Ruby), and was originally designed by Alan Cooper. Many experts regard the emergence of VB as an epoch-making event in the history of software development. In fact, from our current perspective, the functions of VB1.0 are really too weak; (but recently VB6.0 and VB.NET have quite a lot of functions!). But at the time, it was the first "visual" programming software. This made programmers extremely happy, and they all tried to create software on the VB platform. Microsoft also lost no time in launching three versions of VB2.0, VB3.0, and 4.0 within four years. And starting from VB3, Microsoft integrated the ACCESS database driver into VB, which greatly improved VB's database programming capabilities. Starting from VB4, VB also introduced object-oriented programming ideas. VB is powerful and easy to learn. Moreover, VB also introduces the concept of "control", so that a large number of already compiled VB programs can be used directly by us. The DOS version of VB1.0, VB1.0, was released in 1991. This advancement in connecting programming languages ??and user interfaces was called Tripod (sometimes called Ruby), and was originally designed by Alan Cooper in 2002 for Visual Basic .NET 2002 ( v7.0) came out, Visual Basic .NET 2003 (v7.1) came out in 2003, Visual Basic 2005 (v8.0) came out on November 7, 2005, and at the same time a free simplified version of Visual Basic 2005, Visual Basic 2005 Express, was launched Edition is for Visual Basic beginners and students.

The "significant" advantage of VB 2005 is that you can directly write XP-style buttons and other controls. However, the small program written by it takes up nearly 10MB of memory.

After several years of development, it has become a professional development language and environment. Users can quickly create Windows programs with Visual Basic and can now write enterprise-level client/server programs and powerful database applications.

VB will attract more praise and criticism, and will continue to be used by a large number of users and programmers. It is very suitable for developing programs with a friendly interface (such as data for terminals), but it is not suitable for developing other programs (such as joint calculation programs).

Language features

A typical VB process The central idea of ??VB is to be easy to use for programmers, whether they are novices or experts. VB uses a GUI system that can easily create applications, but can also develop fairly complex programs. A VB program is a combination of form-based visual component arrangements, and code is added to specify the properties and methods of the components.

Because some of the default properties and methods are already defined in the component, programmers can complete a simple program without writing much code. In past versions, the performance issue of VB programs has always been put on the table, but with the rapid increase in computer speed, there are fewer and fewer debates about performance.

The addition and change of form controls can be achieved using drag-and-drop technology. A toolbox filled with controls displays the available controls (such as text boxes or buttons). Each control has its own properties and events. Default property values ??are provided when the control is created, but the programmer can also Change. Many property values ??can be changed with the user's actions and modifications during runtime, thus forming a dynamic program. For example, code that can change the position of the control is added to the form's size change event. , whenever the user changes the window size during runtime, the control will also change its position. By adding the corresponding code to the text change event in the text box, the program can automatically translate or prevent the input of certain characters when text is entered. .

A VB program can contain one or more forms, or a main form and multiple subforms, similar to the operating system's dialog window with few functions (for example, no. Maximize and minimize buttons for the form) can be used to provide pop-up functionality.

VB components can have user interfaces or not. This allows the server-side program to handle the added modules.

VB uses the parameter calculation method to perform garbage collection. This method contains a large number of objects and provides basic object-oriented support. As more and more components appear, programmers can choose what they need. Extension library. Unlike some languages, VB is not case-sensitive, but can automatically convert keywords to standard case and force the variable names of entities in symbol table entries to follow the writing rules of strings. Comparison is case-sensitive, but this function can be turned off.

VB allows a large number of external controls to have their own living space. A large number of third-party controls are also provided for VB. and methods of reusing these controls, but due to language issues, it is not simple to create another one from one application.

Terminology

You will often hear the following when discussing Visual Basic. terminology, so a basic understanding of these terms is very helpful.

Control - simply put, a control is a graphical tool that constitutes or builds a Visual Basic application, including forms, buttons, and check boxes. Box, list box, data control, table control, picture control, etc.

Events - Examples of events triggered by the user or the operating system include keystrokes and mouse clicks. ), double-click the mouse (DblClick), a time limit, or receive data from a port.

Method - Program code embedded in the object definition that defines how the object processes information and responds to an event. For example. , a database object has methods to open a record set and move from one record to another. It contains properties that define its characteristics, methods that define its tasks, and methods that identify the events it can respond to. Controls and forms are Visual. Examples of all objects in Basic.

Object - A control, form, etc. can be regarded as an object.

Procedure - a piece of code written to complete certain specific tasks. Procedures are usually used to respond to specific events, and can also be used as user-defined functions in applications.

Attributes - Attributes are specific descriptions of the properties of each object that make up the user interface. For example, the size, position, color, width, height, etc. mentioned in the above "object" are all called properties of the control. Properties determine an object's appearance and sometimes its behavior. Most of the properties of the object have been defined in advance in VB, but some properties need to be defined during the application process.

Properties can provide data to objects and retrieve information from objects.

Limitations of VB

Inheritance. VB5 and VB6 are both object-oriented programming languages, but do not contain inheritance features. VB provides special class functions, but it still cannot meet the needs of programmers. VB.net includes all object-oriented features.

Multi-threading support (VB.Net 2002 and later versions support multi-threading technology.)

Exception handling. Try-Catch-Finally is used in VB.net to handle exceptions. There is only the "On Error Goto line" statement in VB.

Support for pointers is very limited.

VB can only support 8 to 32-bit integers, and many languages ??have unlimited support.

VB does not allow immutable variables in any array.

VB does not support the above features, and programmers need to construct their own methods to achieve similar functions.

Controversy

Opposition:

VB is a language full of controversy: many programmers have strong feelings about the quality of VB programs. Many people think that VB is not suitable for them to use, thinking that it is a language for children and novice programmers. It has been a simple language since its design. Some features in C and Java do not appear in VB. While feeling the convenience and speed of development, some functions such as type and declaration checking at compile time are turned off by default. In this way, some programmers lament the ease of use of VB and generally watch with frustration the occurrence of errors similar to "undefined type".

Some critics believe that the simple nature of VB makes it harmful in the future. Many people have taught themselves VB, but have not learned good programming habits. When VB enters the classroom, students will not learn many basic programming techniques and structures because many techniques are already included in components visible to the user. There is no need to learn standard programming habits, because VB has visual characteristics, which leads to the generation of some inexplicable codes. Moreover, many error and warning checks are turned off by default, making it difficult for programmers to find hidden errors. Experienced programmers will turn on these options when programming in VB.

Many critics criticized Microsoft for simply copying BASIC ideas into VB. The famous computer scientist Edsger Dijkstra once said a famous saying: "If a student first learned BASIC, it is almost impossible for him to learn excellent programming: because these people have given up hope of Nirvana." (Dijkstra treats Fortran, PL/ 1. COBOL and APL are also merciless)

Another joke is: "Real programmers don't use BASIC. Only children under 12 years old use it."

Not really. Very simple, the programs it develops can only run in Microsoft Windows.

Too big. Visual Studio requires several disks to install. The VB program also requires a 1.4M runtime library when running.

There is an error in the IDE.

VB cannot integrate the basic API of Windows very well. In many cases, low-level computing "tricks" have to be used for programming. The low-level memory operations of C language are much simpler than those of VB.