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79 terms

Visual Basic

STUDY
PLAY
line continuation character
the underscore(_); used to break up a long instruction into two or more physical lines in the Code Editor window
Keywords
are words that have special meaning in Visual Basic. They cannot be used as variable names
Accumulator
is a numeric variable that totals numbers
ByVal parameter
When a variable argument is passed to a ByVal parameter, just the value of the argument is passed.
Sub Procedures
can contain one or more parameters in is procedure header, block of code that performs a specific task, processed only when you call them, avoid duplicating code, allow large complex applications to be broken down
Boolean Expression
an expression that evaluates to either True or False is said to have Boolean data type.
String literal
a sequence of characters surrounded by quotation marks
Pseudocode
Uses English-like phrases with some Visual Basic terms to outline the program.
String variable
a name to which a string value can be assigned.
Two-dimensional arrays
store a table of items of the same type
Integer
data type used for variables that hold only whole numbers
ElseIf clauses
An extension of the If block allows for more than two possible alternatives
Flag
is a variable that keeps track of whether a certain situation has occurred
Visual Basic
a programming environment from Microsoft in which a programmer uses a graphical user interface (GUI) to choose and modify preselected sections of code written in the BASIC programming language.
Local scope
variables declared inside an event procedure are only available in the event procedure in which they are declared
Named constants
a special constant whose value does not change during the program execution.
Relational operators
are binary meaning they require an operand on both sides of the operator. Value of a relational expression will always be True or False. Expressions are evaluated from left to right with no order of operations
Variable
a name used to refer to data. Names must begin with a letter or an underscore and many contain letters, digits, and underscores. DIM statements declare this, specify the data types of this, and assign initial values to this.
Counter
is a numeric variable that keeps track of the number of items that have been processed.
Hierarchy Chart
Shows how the different parts of a program relate to each other.
Comments
specify the intent of the program, the purpose of variables and the task performed by individual portions of the program. Are created by beginning the line with '
Class-level scope
variables declared outside an event procedure are available to every event procedure.
Syntax error
an error in spelling, punctuation or omission. The program cannot run until these are corrected.
Source Code and object code
refer to the "before" and "after" versions of a computer program that is compiled (see compiler) before it is ready to run in a computer. The source code consists of the programming statements that are created by a programmer with a text editor or a visual programming tool and then saved in a file.
Parameters
variables appearing in the top line of the function procedure
Label Control
Used to identify the contents of a text box.
Logic error
occurs when the program does not perform the way it was intended.
String.Length
a property that gives the number of characters in a string
ANSI Character Set
a numeric representation for every key on the keyboard and for other assorted characters.
Concatenation
Joining of Visual Basic string variables to make longer strings using the '&' operator.
Select Case block
an efficient decision-making structure that simplifies choosing among several actions. It avoids complex nested If constructs.
Selector
determines the value of an expression Select Case choices
Substring
a string is a sequence of consecutive characters from the string - part of the string
Logical Operators
are used with Boolean expressions
Program
a sequence of instructions
String.ToUpper
changes all characters in a string to upper case
Compiler (Compiling)
a process of translating the code statements that make up a a computer application into a format that can be executed (run) by the computer operating system.
Do loop
repeats a sequence of statements either as long as or until a certain condition is true
Sequential search
Searching successive elements of an ordered list beginning with the first element
Variable
(or simple variable) is a name to which Visual Basic can assign a single value.
If Block
the program will take a course of action based on whether a condition is true.
Looping
a series of instructions are executed over and over
Declaration statement
declares the name and type of the variable to be used in the program
Algorithm
a step by step series of instructions to solve a problem
Hardware
the physical components of a computer
Return expression
the value returned by the function
Decision
if the answer to a question is "Yes" then one group of instructions is executed. If the answer is "No," then another is executed
Loop
is structures in programming used to repeat a sequence of statements a number of times.
Event
an action, such as the user clicking on a button.
Subscript
a unique number that identifies each variable in a one-dimensional array
File
holds programs or data. Its name usually consists of letters, digits, and spaces.
Element
an individual variable in the array
Numeric literal
numbers processed by the program
Infinite loops
loops that never end
Program Comment
a statement embedded within an application that contains a text string that is visible to the programmer but ignored by the application.
Call statement
is the statement that invokes a Sub procedure.
Nested If blocks
When one If block is contained inside another If block, the structure is referred to as.
Function procedures
(aka user-defined functions) always return one value
Text Box Control
Used for input and output
Option Strict
disallowsnumeric variables to be assigned strings and vice versa
User
any person who uses the program written by the programmer
Software
The instructions that tell the computer what to do
String.ToLower
changes all characters in a string to lower case
Flowchart
Graphically depicts the logical steps to carry out a task and shows how the steps relate to each other.
Array variable
is a collection of simple variables of the same type to which Visual Basic can efficiently assign a list of values.
Block-level scope
A variable declared inside an If … Then or Select Case block has block level scope and the variable cannot be referred to outside the block.
Condition
an expression involving relational and/or logical operators
Increment
means to add one to the variable
Nested loop
statements inside a loop can contain another loop
valueList
itemizes the values of the selector for which the action should be taken.
Programmer
the person who solves the problem and writes the instructions for the computer
Sequence
follow instructions from one line to the next without skipping over any lines
Scope
a variable is the portion of the program that can refer to it
Numeric expression
a combination of literals, variables and arithmetic operations that can be evaluated to yield a number
ByRef
When a variable argument is passed to a ByRef parameter, the parameter is given the same memory location as the argument.
Binary search
Given: an array in ascending order and a sought-after value, quarry, that may be in the array. Repeatedly halve the range of indices where quarry might be found. Halving routine looks at the middle value of the current range and compares it to quarry with =, >, and <.
Folder
contains files and other folders (called subfolders).
Run-time error
an error that occurs while the program is running as a result of the program being unable to execute the task.
Variable Scope:
In Sub procedures, defined same as in event procedures.