Visual Basic/Glossary< Visual Basic
An alphabetical list of definitions crossreferenced to more thorough explanations in the main text or in external documents.
- In computing jargon an argument is one of the pieces of data passed to a procedure. Another name is parameter.
- assign, assigning, assignment
- Assignment is one of the fundamental operations of computing. All it means is copying a value into the memory location pointed at by a variable. The value can be a literal or the value of some other variable, q.v. Assignment
- Declares an argument to a procedure as a pointer to the argument instead of as a copy of the value of the argument. This allows the procedure to permanently change the variable. If neither ByRef or ByVal is stated, ByRef is assumed by the compiler.
- Declares an argument to a procedure as a copy of the value of the argument. The value of the original variable cannot be changed by the procedure. The value of the newly created variable can be changed within the procedure, but this does not affect the variable it was copied from. Programs are more robust if variables are declared ByVal whenever possible since this means that an argument will not be unexpectedly changed by calling a function. This also results in a faster program (see pg 758 of the Microsoft Visual Basic 6 Programmer's Guide).
- compiler directives
- These are instructions included in the text of the program that affect the way the compiler behaves. For instance it might be directed to include one or another version of a piece of code depending on whether the target operating system is Windows 95 or Windows XP.
- Immediate Windows
- This is the window in the IDE which receives output from Debug.Print. See IDE
- Operands and Operators
- An operand is operated on by an operator. Expressions are built of operands and operators. For instance in this expression:
a = b + c
there are three operands (a, b, and c) and two operators (= and +).
- ragged array
aRagged = Array(Array(1, 2, 3), Array(1, 2))
- Such arrays are inefficient in Visual Basic because they are implemented as Variants but functionaly identical arrays can be created as instances of a class and can be made much more efficient both in storage space and execution time, although not quite as efficient as C arrays.
- real number
- A variable that can hold a real number is one that can hold a number that can have any value including fractional value. In computer languages variables only approximate real numbers because the irrational numbers are also real, see Real number. In Visual Basic Classic there are two real number types: Single and Double, see Data Types
- A variable that holds a pointer to a value rather than holding the the value itself. In strict Visual Basic usage only object references work like this.