Computer Programming Concepts and Visual Basic David I. Schneider

DEFINT, DEFLNG, DEFSNG, DEFDBL, DEFSTR, DEFCUR, DEFVAR, DEFBYTE,
DEFBOOL, DEFDATE, DEFOBJ A variable can be assigned a type by either a type-declaration
tag or an As clause. A statement of the form DefInt letter specifies that any “untyped”
variable whose name begins with the specified letter will have integer type. A statement of
the form DefInt letter1-letter2 specifies that all “untyped” variables whose names begin with
a letter in the range letter1 through letter2 will have integer type. The statements DefLng,
DefSng, DefDbl, DefStr, DefCur, DefVar, DefByte, DefBool, DefDate, and DefObj specify
the corresponding types for long integer, single-precision, double-precision, string, currency,
variant, byte, boolean, date, and object variables, respectively. DefType statements are
placed in the (Declarations) section of (General). [variant]
DELETE The Delete method for a data control deletes the current record.
DIM The statement Dim arrayName(m To n) As variableType declares an array with subscripts
ranging from m to n, inclusive, where m and n are in the normal integer range of
–32768 to 32767. The variableType must be Integer, Long, Single, Double, Currency, String,
String*n, Variant, Boolean, Byte, Date, or a user-defined type. A statement of the form Dim
arrayName(m To n, p To q) As variableType declares a doubly subscripted, or two-dimensional,
array. Three- and higher-dimensional arrays are declared similarly. If m and p are
zero, the preceding Dim statements may be changed to Dim arrayName(n) As variableType
and Dim arrayName(n, q) As variableType. The statement Dim arrayName( ) As variable-
Type defines an array whose size is initially unknown but must be established by a ReDim
statement before the array can be accessed. The statement Dim variableName As variable-
Type specifies the type of data that will be stored in variableName. Variables and arrays
Dimmed in the (Declarations) section of (General) are available to all procedures. In procedures,
Dim is used to declare variables, but ReDim is often used to dimension arrays.
[dynamic vs. static] [variant]
DIR If fileTemplate specifies a file (or a collection of files by including ? or *), then the
value of the function Dir(fileTemplate) is the filename of the first file matching the pattern
specified by fileTemplate. If this value is not the null string, the value of the function Dir is
the name of the next file that matches the previously specified pattern. For example, the
value of Dir(“*.VBP”) will be the name of the first file in the current directory of the default
drive whose name has the .VBP extension. [directories] [filespec]
DO/LOOP A statement of the form Do, Do While cond, or Do Until cond is used to mark
the beginning of a block of statements that will be repeated. A statement of the form Loop,
Loop While cond, or Loop Until cond is used to mark the end of the block. Each time a
statement containing While or Until followed by a condition is encountered, the truth value
of the condition determines whether the block should be repeated or whether the program
should jump to the statement immediately following the block. A Do loop may also be exited
at any point with an Exit Do statement.
DOEVENTS Executing the statement DoEvents permits Visual Basic to act on any events
may have occurred while the current event procedure has been executing.
DOUBLE A variable of type Double requires 8 bytes of memory and can hold 0, the numbers
from 4.9406520 � 2010 –324 to 1.797693134862316 � 10308 with at most 17 significant
digits and the negatives of these numbers. Double values and variables may be indicated by
the type tag #: 2.718281828459045#, Pi#.
DRAWMODE The property DrawMode determines whether graphics are drawn in black,
white, foreground color, or some interaction of these colors with the current contents of the
form or picture box. The following table lists the allowed values for the DrawMode property
and the rules for what RGB color number will be assigned at a given point when the RGB
color number for the color currently displayed at that point is display and the RGB color
number for the draw color is draw. [color]
Appendix C 429