Computer Programming Concepts and Visual Basic David I. Schneider

438 Computer Programming Concepts and Visual Basic
IF (single line) A statement of the form If condition Then action causes the program to take
the specified action if condition is true. Otherwise, execution continues at the next line. A
statement of the form If condition Then action1 Else action2 causes the program to take
action1 if condition is true and action2 if condition is false.
IF TYPEOF To test for the type of a control when the control name is passed to a procedure,
use If TypeOf controlName Is controlType Then action1 Else action2 in either the single line
or block form of the If statement. ElseIf TypeOf is also permitted. For controlType, use one
of the control names that appear in the Form Design ToolBox (CommandButton, Label,
TextBox, etc.)—for example, If TypeOf objectPassed Is Label Then. . . .
IMP The logical expression condition1 Imp condition2 is true except when condition1 is
true and condition2 is false. For example, (3”a”) is true because both 3”a”are true, and (“apple”>”ape”) Imp (“earth”> “moon”) is false because
“apple”>”ape”is true but “earth”>”moon”is false. Imp is an abbreviation for “logically
implies.”
INDEX When a control is part of a Control array, it is identified by the number specified
by its Index property.
INPUT The statement strVar = Input(n, m) assigns the next n characters from the file with
reference number m (opened in Input or Binary mode) to strVar.
INPUT # The statement Input #n, var reads the next item of data from a sequential file that
has been opened for Input with reference number n and assigns the item to the variable var.
The statement Input #n, var1, var2, . . . reads a sequence of values and assigns them to the
variables.
INPUTBOX The value of the function InputBox(prompt) is the string entered by the user in
response to the prompt given by prompt. The InputBox function automatically displays the
prompt, a text box for user input, an OK button, and a Cancel button in a dialog box in the
center of the screen. If the user selects Cancel, the value of the function is the null string (“”).
For greater control, use the function InputBox(prompt, title, defaultStr, xpos, ypos), which
places the caption title in the title bar of the dialog box, displays defaultStr as the default
value in the text box, and positions the upper-left corner of the dialog box at coordinates
(xpos, ypos) on the screen. [coordinate systems]
INSTR The value of the function InStr(str1, str2) is the position of the string str2 in the
string str1. The value of InStr(n, str1, str2) is the first position at or after the nth character
of str1 that the string str2 occurs. If str2 does not appear as a substring of str1, the value is
0.
INT The value of the function Int(x) is the greatest whole number that is less than or equal
to x.
INTEGER A variable of type Integer requires 2 bytes of memory and can hold the whole
numbers from –32,768 to 32,767. Integer values and variables may be indicated by the type
tag %: 345%, Count%.
INTERVAL The Interval property of a Timer control is set to the number of milliseconds (1
to 65535) required to trigger a Timer event.
ISDATE The value of the function IsDate(str) is True if the string str represents a date
between January 1, 100 and December 31, 9999. Otherwise, the value is False. [date]
ISEMPTY The value of the function IsEmpty(v) is True if v is a variable of unspecified type
(that is, is a variant) that has not yet been assigned a value. In all other cases the value of
IsEmpty is False. [variant]
ISNULLThe value of the function IsNull(v) is True if v is a variant variable that has been
assigned the special value Null. In all other cases the value of IsNull is False. [variant]