6.5 Other String Manipulation Functions
Here are some other string manipulation functions which you can use:
Asc(String) returns the ASCII code corresponding to the first letter in a string. For example,
Asc("I love Visual Basic") is 73 since the ASCII code for "I" is 73.
Chr(AsciiCode) returns the character corresponding to the ASCII code. For example, Chr(73) is
"I".
Asc and Chr are very helpful when the programmer wants to encode a string. For example,
changing all a's to d's, b's to e's, c's to f's would require you to add 3 to the ASCII code of each
character and then convert it back to a letter.
Left(string, length) returns a specified number of characters from the left side of a string.
For example:
Dim Hello As String, NewString As String
Hello = "I love Visual Basic"
NewString = Left(Hello, 1) --> NewString = "I"
NewString = Left(Hello, 7) --> NewString = "I love "
Len(string) returns the length of the string. This is particularly helpful in For Loops that must go
through each character in the string one by one.
For example: For Num = 1 to Len(Hello0
LTrim(string) returns a copy of the string without leading spaces.
RTrim(string) returns a copy of the string without trailing spaces.
Trim(string) returns a copy of the string without leading or trailing spaces.
Str(number) returns a string representation of a number. This is helpful in string manipulation
of numbers. We need to convert numbers to strings in order to use all of this string manipulation
functions on them. But, after string manipulating, we may need to convert them back to numbers
again so that they can be added, subtracted, etc.
Val(string) returns the numeric value of a string. This is often used with Str since numbers that
are converted to strings may need to be converted back to numbers so that numeric evaluations
can occur.
StrConv(string, type_of_conversion) converts the string to upper or lower case. If the type of
conversion is 1, then it puts the string into uppercase; if the type of conversion is 2, then it puts
the string into lowercase; if the type of conversion is 3, it uppercases the first letter of every word
in a string.
String(number, character) returns a repeating character string of the length specified. Number
is the length of the returned string and character specifies the character code or string
expression whose first character is used to build the return string.
Example:
Hello = String(5, "*") -->output is *****
Hello = String(3, "Happy") -->output is HHH
Activity 6.5.1
Enter the following into the Form_Load() and make note of the output
Dim Word As String, LittleWord As String
Dim Length, Num as Integer
Word = "COMPUTER"
Length = Len(Word)
For Num = 1 to Length
LittleWord = Mid(Word, Num, 1)
Debug.Print Asc(LittleWord)
Next Num
Activity 6.5.2
Ex. 2 Converting Strings to Real/Integers and Vice-Versa
Enter the following into the Form_Load() and make note of the output
Dim Num1As String, Num2 As String
Dim Num3 As Integer
Num1 = "3"
Num2 = "25"
Num3 = 6
MsgBox "The sum is "& Val(Num1) + Val(Num2) + num3
Activity 6.5.1
Ex. 3 Finds the Sum of the Squares of the Digits that make up a Number
Enter the following into the Form_Load() and make note of the output
For this example, you need to create a form design that will allow the user to enter a number.
Once you get the number stored in a textbox, this procedure is called to find the Sum of the
Squares of the Number. This procedure is unlike the ones you have seen before because it is not
connected to a particular event such as Click or KeyPress. Instead, it is called from within an
event procedure or from the Form_Load. We will look at this in more detail later. For now, just
enjoy the For Loop which finds the sum of the squares of the digits. For example, the sum of the
squares of the digits of 56 is 61 because 5 * 5 + 6 * 6 = 25 + 36 = 61.
Public Sub SumofSquares(Sum As Integer, Num As Integer)
Dim Digit As Integer, Length As Integer
Dim Hello As String
Length = Len(Num)
For Digit = 1 To Length
Hello = Mid(Num, Digit, 1)
Sum = Sum + (Val(Hello)) ^ 2
Next Digit
End Sub