Visual Basic 2010 Lesson 8- String Manipulation

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Generally we have to deal with two types of data, the numeric and the non-numeric data types. The non-numeric data again divided in to a few types, the most common one being text, or string. Examples of string are words, sentences, names, addresses, gender, cities, book titles and many more. In this lesson, we shall learn how to process and manipulate strings in visual basic 2010

8.1 String Manipulation Using + and & signs.

In Visual Basic 2010 ,Strings can be manipulated using the & sign and the + sign, both perform the string concatenation which by combining two or more smaller strings into larger strings. For example, we can join “Visual” and “Basic” into “Visual Basic” using “Visual”&”Basic” or “Visual “+”Basic”, as shown in the example below

Example 8.1(a)

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim text1, text2, text3 As String
text1 = “Visual”
text2 = “Basic”
text3 = text1 + text2
Label1.Text = text3End Sub




The line text3=text1+ text2 can be replaced by text3=text1 & text2 and produce the same output. However, if one of the variables is declared as numeric data type, you cannot use the + sign, you can only use the & sign.

Example 8.1(b)

Dim text1, text3 as string
Dim Text2 As Integertext1 = “Visual”

text2=22

text3=text1+text2

Label1.Text = text3




This code will produce an error because of data mismatch.However, using & instead of + will be all right.

Dim text1, text3 as string

Dim Text2 As Integer

text1 = “Visual”

text2=22

text3=text1 & text2

Label1.Text = text3

You can combine more than two strings to form a larger strings, like the following example:

Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim text1, text2, text3, text4, text5, text6 As String

text1 = “Welcome”
text2 = ” to”
text3 = ” Visual”
text4 = ” Basic”
text5 = ” 2010″
text6 = text1 + text2 + text3+text4+text5
Label1.Text = text6

End Sub
End Class

Running the above program will produce the following screen shot.


8.2 String Manipulation Using Visual Basic 2010 Built-in Functions

A function is similar to a normal procedure. However, the main purpose of a function is to accept an input and return a value. The value then is passed on to the main program to finish the in this lesson here and will explain the rest of them in later lessons.

8.2 (a) The Len Function

The length function returns an integer value equals to the length of a phrase or a sentence, including the empty spaces. The syntax is
Len (“Phrase”)
For example,
Len (Visual Basic) = 12 and Len (welcome to VB tutorial) = 22

Example 8.3

Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Label1.Text = Len(TextBox1.Text)

End Sub
End Class

The output:

8.2(b) The Right Function

The Right function extracts the right portion of a phrase. The syntax for Visual Basic 6 is

Right (“Phrase”, n)

Where n is the starting position from the right of the phase where the portion of the phrase is going to be extracted. For example,

Right(“Visual Basic”, 4) = asic

However, this syntax is not applicable in VB2010. In VB2010, we need use the following syntax

Microsoft.VisualBasic.Right(“Phrase”,n)

Example 8.2(a)

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim text1 As String

text1 = TextBox1.Text

Label1.Text = Microsoft.VisualBasic.Right(text1, 4)

End Sub

The above programme will return four right most characters of the phrase entered into the textbox.

The Output:

*The reason of using the full reference is because many objects have the Right properties so using Right on its own will make it ambiguous to VB2010.

8.2(c)The Left Function

The Left function extracts the left portion of a phrase. The syntax is

Microsoft.VisualBasic.Left(“Phrase”,n)

Where n is the starting position from the left of the phase where the portion of the phrase is going to be extracted. For example,

Microsoft.VisualBasic.Left (“Visual Basic”, 4) = Visu .

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