Computer Programming Concepts and Visual Basic David I. Schneider

Like the numeric functions discussed before, Left, Mid, Right, UCase, and Trim also can
be evaluated for variables and expressions.
EXAMPLE 5
The following program evaluates the functions above for variables and expressions. Note that spaces are
counted as characters.
Private Sub cmdEvaluate_Click()
Dim str1 As String, str2 As String
‘Evaluate functions at variables and expressions.
picResults.Cls
str1 = “Quick as ”
str2 = “a wink”
picResults.Print Left(str1, 7)
picResults.Print Mid(str1 & str2, 7, 6)
picResults.Print UCase(str1 & str2)
picResults.Print “The average ”; Right(str2, 4); “ lasts .1 second.”
picResults.Print Trim(str1); str2
End Sub
[Run and then click the command button. The following is displayed in the picture box.]
Quick a
as a w
QUICK AS A WINK
The average wink lasts .1 second.
Quick asa wink
■ STRING-RELATED NUMERIC FUNCTIONS: LEN, INSTR
The functions Len and InStr operate on strings but produce numbers. The function Len gives
the number of characters in a string. The function InStr searches for the first occurrence of one
string in another and gives the position at which the string is found. Suppose str1 and str2 are
strings. The value of Len(str1) is the number of characters in str1. The value of InStr(str1, str2)
is 0 if str2 is not a substring of str1. Otherwise, its value is the first position of str2 in str1.
Some examples of Len and InStr follow:
Len(“Shenandoah”) is 10. InStr(“Shenandoah”, “nand”) is 4.
Len(“Just a moment”) is 13. InStr(“Just a moment”, “ ”) is 5.
Len(“ ”) is 1. InStr(“Croissant”, “ist”) is 0.
EXAMPLE 6
The following program evaluates functions at variables and expressions. The ninth line locates the position
of the space separating the two names. The first name will end one position to the left of this position
and the last name will consist of all but the first n characters of the full name.
Private Sub cmdAnalyze_Click()
Dim nom As String ‘Name
Dim n As Integer ‘Location of space
Dim first As String ‘First name
Dim last As String ‘Last name ‘
Evaluate functions at variables and expressions.
picResults.Cls
nom = txtFullName.Text
n = InStr(nom, “ ”)
first = Left(nom, n - 1)
Built-In Functions 61