An object that you place on a form to enable or enhance a user's interaction with an application. ActiveX Controls have events and can be incorporated into other controls. These controls have an .ocx file name extension.
American National Standards Institute (ANSI) 8-bit character set used to represent up to 256 characters (0–255) using your keyboard. The first 128 characters (0–127) correspond to the letters and symbols on a standard U.S. keyboard. The second 128 characters (128–255) represent special characters, such as letters in international alphabets, accents, currency symbols, and fractions.
A collection of code and visual elements that work together as a single program. Developers can build and run applications within the development environment, while users usually run applications as executable files outside the development environment.
A set of sequentially indexed elements having the same intrinsic data type. Each element of an array has a unique identifying index number. Changes made to one element of an array don't affect the other elements.
American Standard Code for Information Interchange (ASCII) 7-bit character set used to represent letters and symbols found on a standard U.S. keyboard. The ASCII character set is the same as the first 128 characters (0–127) in the ANSI character set.
An image represented by pixels and stored as a collection of bits in which each bit corresponds to one pixel. On color systems, more than one bit corresponds to each pixel. A bitmap usually has a .bmp file name extension.
A data-aware control that can provide access to a specific field or fields in a database through a Data control. A data-aware control is typically bound to a Data control through its DataSource and DataField properties. When a Data control moves from one record to the next, all bound controls connected to the Data control change to display data from fields in the current record. When users change data in a bound control and then move to a different record, the changes are automatically saved in the database.
A way of passing the address of an argument to a procedure instead of passing the value. This allows the procedure to access the actual variable. As a result, the variable's actual value can be changed by the procedure to which it is passed. Unless otherwise specified, arguments are passed by reference.
A way of passing the value of an argument to a procedure instead of passing the address. This allows the procedure to access a copy of the variable. As a result, the variable's actual value can't be changed by the procedure to which it is passed.
The formal definition of an object. The class acts as the template from which an instance of an object is created at run time. The class defines the properties of the object and the methods used to control the object's behavior.
An object that contains a set of related objects. An object's position in the collection can change whenever a change occurs in the collection; therefore, the position of any specific object in the collection can vary.
A character or symbol indicating a relationship between two or more values or expressions. These operators include less than (<), less than or equal to (<=), greater than (>), greater than or equal to (>=), not equal (<>), and equal (=). Additional comparison operators include Is and Like. Note that Is and Like can't be used as comparison operators in a Select Case statement.
A Visual Basic identifier that is defined using the #Const compiler directive or defined in the host application and used by other compiler directives to determine when or if certain blocks of Visual Basic code are compiled.
A named item that retains a constant value throughout the execution of a program. A constant can be a string or numeric literal, another constant, or any combination that includes arithmetic or logical operators except Is and exponentiation. Each host application can define its own set of constants. Additional constants can be defined by the user with the Const statement. You can use constants anywhere in your code in place of actual values.
An object you can place on a form that has its own set of recognized properties, methods, and events. You use controls to receive user input, display output, and trigger event procedures. You can manipulate most controls using methods. Some controls are interactive (responsive to user actions), while others are static (accessible only through code).
A data type with a range of -922,337,203,685,477.5808 to 922,337,203,685,477.5807. Use this data type for calculations involving money and for fixed-point calculations where accuracy is particularly important. The at sign (@) type-declaration character represents Currency in Visual Basic.
The characteristic of a variable that determines what kind of data it can hold. Data types include Byte, Boolean, Integer, Long, Currency, Decimal, Single, Double, Date, String, Object, Variant (default), and user-defined types, as well as specific types of objects.
A data type used to store dates and times as a real number. Date variables are stored as 64-bit (8-byte) numbers. The value to the left of the decimal represents a date, and the value to the right of the decimal represents a time.
Any expression that can be interpreted as a date, including date literals, numbers that look like dates, strings that look like dates, and dates returned from functions. A date expression is limited to numbers or strings, in any combination, that can represent a date from January 1, 100 – December 31, 9999.
Dates are stored as part of a real number. Values to the left of the decimal represent the date; values to the right of the decimal represent the time. Negative numbers represent dates prior to December 30, 1899.
Any sequence of characters with a valid format that is surrounded by number signs (#). Valid formats include the date format specified by the locale settings for your code or the universal date format.
For example, #12/31/92# is the date literal that represents December 31, 1992, where English-U.S. is the locale setting for your application. Use date literals to maximize portability across national languages.
A data type that contains decimal numbers scaled by a power of 10. For zero-scaled numbers, that is, numbers with no decimal places, the range is +/-79,228,162,514,264,337,593,543,950,335. For numbers with 28 decimal places the range is +/-7.9228162514264337593543950335. The smallest non-zero number that can be represented as a Decimal is 0.0000000000000000000000000001.
Note that at this time the Decimal data type can only be used within a Variant. You cannot declare a variable to be of type Decimal. You can, however, create a Variant whose subtype is Decimal using the CDec function.
Provides a visual design window in the Visual Basic development environment. You can use this window to design new classes visually. Visual Basic has built-in designers for forms. The Professional and Enterprise editions of Visual Basic include designers for ActiveX controls and ActiveX documents.
The time during which you build an application in the development environment by adding controls, setting control or form properties, and so on. In contrast, during run time, you interact with the application like a user.
A data type that holds double-precision floating-point numbers as 64-bit numbers in the range -1.79769313486231E308 to -4.94065645841247E-324 for negative values; 4.94065645841247E-324 to 1.79769313486232E308 for positive values. The number sign (#) type-declaration character represents the Double in Visual Basic.
A whole number in the range 0 – 65,535 that corresponds to the Number property setting of the Err object. When combined with the Description property setting of the Err object, this number represents a particular error message.
An object that is the source of events that occur in response to an action. An event source object is returned by a property. For example, the CommandBarEvents property returns the CommandBarEvents object.
Number used in the Open statement to open a file. Use file numbers in the range 1–255, inclusive, for files not accessible to other applications. Use file numbers in the range 256–511 for files accessible from other applications.
The ability to receive mouse clicks or keyboard input at any one time. In the Microsoft Windows environment, only one window, form, or control can have this ability at a time. The object that "has the focus" is normally indicated by a highlighted caption or title bar. The focus can be set by the user or by the application.
A file in a Visual Basic project with an .frm file name extension that can contain graphical descriptions of a form; its controls and their property settings; form-level declarations of constants, variables, and external procedures; and event and general procedures.
A method that operates on an object such as a Form, PictureBox, or Printer, and performs run-time drawing operations such as animation or simulation. The graphics methods are Circle, Cls, Line, PaintPicture, Point, Print, and PSet.
A graphical representation of an object or concept; commonly used to represent minimized applications in Microsoft Windows. An icon is a bitmap with a maximum size of 32 x 32 pixels. Icons have an .ico file name extension.
A data type that holds integer variables stored as 2-byte whole numbers in the range -32,768 to 32,767. The Integer data type is also used to represent enumerated values. The percent sign (%) type-declaration character represents an Integer in Visual Basic.
A constant provided by an application. Visual Basic constants are listed in the object library and can be viewed with the Object Browser. Because you can't disable intrinsic constants, you can't create a user-defined constant with the same name.
The combination of a space followed by an underscore ( _) used in the development environment to extend a single logical line of code to two or more physical lines. However, you can't use a line-continuation character to continue a line of code within a string expression.
Used to identify a single line of code. A line label can be any combination of characters that starts with a letter and ends with a colon (:). Line labels are not case sensitive and must begin in the first column.
The set of information that corresponds to a given language and country/region. The code locale setting affects the language of terms such as keywords and defines locale-specific settings such as the decimal and list separators, date formats, and character sorting order.
The system locale setting affects the way locale-aware functionality behaves, for example, when you display numbers or convert strings to dates. You set the system locale using the Control Panel utilities provided by the operating system.
Although the code locale and system locale are generally set to the same setting, they may differ in some situations. For example, in Visual Basic, Standard Edition and Visual Basic, Professional Edition, the code is not translated from English-U.S. The system locale can be set to the user's language and country/region, but the code locale is always set to English-U.S. and can't be changed. In this case, the English-U.S. separators, format placeholders, and sorting order are used.
A programming error that can cause code to produce incorrect results or stop execution. For example, a logic error can be caused by incorrect variable names, incorrect variable types, endless loops, flaws in comparisons, or array problems.
A file that stores an image as graphical objects such as lines, circles, and polygons rather than as pixels. There are two types of metafiles, standard and enhanced. Standard metafiles usually have a .wmf file name extension. Enhanced metafiles usually have a .emf file name extension. Metafiles preserve an image more accurately than pixels when the image is resized.
A variable declared outside Function, Sub, or Property procedure code. Module variables must be declared outside any procedures in the module. They exist while the module is loaded and are visible in all procedures in the module.
An argument that has a name that is predefined in the object library. Instead of providing a value for each argument in a specified order expected by the syntax, you can use named arguments to assign values in any order. For example, suppose a method accepts three arguments:
DoSomeThing namedarg1, namedarg2, namedarg3
By assigning values to named arguments, you can use the following statement:
Any intrinsic numeric data type (Byte, Boolean, Integer, Long, Currency, Single, Double, or Date) or any Variant numeric subtype (Empty, Integer, Long, Single, Double, Currency, Decimal, Date, Error, Boolean, or Byte).
A list box at the upper-left corner of the Code window that lists the form and controls in the form to which the code is attached, or a list box located at the top of the Properties window that lists the form and its controls.
An expression that specifies a particular object and can include any of the object's containers. For example, an application can have an Application object that contains a Document object that contains a Text object.
A file with the .olb extension that provides information to Automation controllers (like Visual Basic) about available objects. You can use the Object Browser to examine the contents of an object library to get information about the objects provided.
A module that contains code specific to an object, for example, class module, form module, and document module. Object modules contain the code behind their associated objects. The rules for object modules differ from those for standard modules.
A type of object exposed by an application through Automation, for example, Application, File, Range, and Sheet. Use the Object Browser or refer to the application's documentation for a complete listing of available objects.
A named sequence of statements executed as a unit. For example, Function, Property, and Sub are types of procedures. A procedure name is always defined at module level. All executable code must be contained in a procedure. Procedures can't be nested within other procedures.
A window that displays a list of the form, class, and standard modules; the resource file; and references in your project. Files with .ocx and .vbx file name extensions aren't displayed in the Project window.
A procedure that creates and manipulates properties for a class module. A Property procedure begins with a Property Let, Property Get, or Property Set statement and ends with an End Property statement.
Variables declared using the Public statement are visible to all procedures in all modules in all applications unless Option Private Module is in effect. In that case, the variables are public only within the project in which they reside.
The project you directly create a link to from the current project you are working on. A project referenced by one of the current project's directly referenced projects is called an indirectly referenced project. Its Public variables are not accessible to the current project except through qualification with its project name. Any combination of direct and indirect references between projects is valid as long as they do not result in a complete cycle.
The current project. How you create a link to a project depends on the host application. For example, to directly reference a project in Microsoft Excel, select the project from the References dialog box of the Tools menu. Public variables in a directly referenced project are visible to the directly referencing project, but Public variables in a directly referencing project are not visible to a directly referenced project.
In Microsoft Windows version 3.1, OLE registration information and file associations are stored in the registration database, and program settings are stored in Windows system initialization (.ini) files. In Microsoft Windows 95, the Windows registry serves as a central configuration database for user, application, and computer-specific information, including the information previously contained in both the Windows version 3.1 registration database and .ini files.
A file in a Visual Basic project with an .res file name extension that can contain bitmaps, text strings, or other data. By storing this data in a separate file, you can change the information without editing your code. Only one resource file can be associated with a project.
Defines the visibility of a variable, procedure, or object. For example, a variable declared as Public is visible to all procedures in all modules in a directly referencing project unless Option Private Module is in effect. When Option Private Module is in effect, the module itself is private and therefore not visible to referencing projects. Variables declared in a procedure are visible only within the procedure and lose their value between calls unless they are declared Static.
A data type that stores single-precision floating-point variables as 32-bit (4-byte) floating-point numbers, ranging in value from -3.402823E38 to -1.401298E-45 for negative values, and 1.401298E-45 to 3.402823E38 for positive values. The exclamation point (!) type-declaration character represents a Single in Visual Basic.
A module containing only procedure, type, and data declarations and definitions. Module-level declarations and definitions in a standard module are Public by default. A standard module is referred to as a code module in earlier versions of Visual Basic.
A syntactically complete unit that expresses one kind of action, declaration, or definition. A statement generally occupies a single line, although you can use a colon (:) to include more than one statement on a line. You can also use a line-continuation character (_) to continue a single logical line onto a second physical line.
A data type consisting of a sequence of contiguous characters that represent the characters themselves rather than their numeric values. A String can include letters, numbers, spaces, and punctuation. The String data type can store fixed-length strings ranging in length from 0 to approximately 63K characters and dynamic strings ranging in length from 0 to approximately 2 billion characters. The dollar sign ($) type-declaration character represents a String in Visual Basic.
Any expression that evaluates to a sequence of contiguous characters. Elements of a string expression can include a function that returns a string, a string literal, a string constant, a string variable, a string Variant, or a function that returns a string Variant (VarType 8).
A feature that checks your code for correct syntax. If the syntax checking feature is enabled, a message is displayed when you enter code that contains a syntax error and the suspect code is highlighted.
An error that occurs when you enter a line of code that Visual Basic doesn't recognize.
Note that syntax rules for individual keywords are defined in the Syntax section of the associated Help topic. To get Help on a keyword from within the development environment, select the keyword and press F1.
A unit of screen measurement equal to 1/20 point. A twip is a screen-independent unit used to ensure that placement and proportion of screen elements in your screen application are the same on all display systems. There are approximately 1440 twips to a logical inch or 567 twips to a logical centimeter (the length of a screen item measuring one inch or one centimeter when printed).
A file or component within another file that contains standard descriptions of exposed objects, properties, and methods that are available for Automation. Object library files (.olb) contain type libraries.
International Standards Organization (ISO) character standard. Unicode uses a 16-bit (2-byte) coding scheme that allows for 65,536 distinct character spaces. Unicode includes representations for punctuation marks, mathematical symbols, and dingbats, with substantial room for future expansion.
Any data type defined using the Type statement. User-defined data types can contain one or more elements of any data type. Arrays of user-defined and other data types are created using the Dim statement. Arrays of any type can be included within user-defined types.
A named storage location that can contain data that can be modified during program execution. Each variable has a name that uniquely identifies it within its scope. A data type can be specified or not.
Variable names must begin with an alphabetic character, must be unique within the same scope, can't be longer than 255 characters, and can't contain an embedded period or type-declaration character.
A special data type that can contain numeric, string, or date data as well as user-defined types and the special values Empty and Null. The Variant data type has a numeric storage size of 16 bytes and can contain data up to the range of a Decimal, or a character storage size of 22 bytes (plus string length), and can store any character text. The VarType function defines how the data in a Variant is treated. All variables become Variant data types if not explicitly declared as some other data type.
A user-defined expression that enables you to observe the behavior of a variable or expression. Watch expressions appear in the Watch window of the Visual Basic Editor and are automatically updated when you enter break mode. The Watch window displays the value of an expression within a given context. Watch expressions are not saved with your code.