Visual Basic 2012 Lesson 8- String Manipulation

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[Lesson 7] << [CONTENTS] >> [Lesson 9]

8.1 String Manipulation Using + and & signs.

In Visual Basic 2012, strings can be manipulated using the & sign and the + sign, both perform the string concatenation which means combining two or more smaller strings into larger strings. For example, we can join “Visual”,”Basic” and “2012” into “Visual Basic 2012” using “Visual”&”Basic” or “Visual “+”Basic”, as shown in the Examples below

Example 8.1(a)

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 As String
 text1 = "Visual"
 text2 = "Basic"
 text3="2012"
 text4 = text1 + text2+text3
 MsgBox(text4)

End Sub
End Class

The line text4=text1+ text2 + text3 can be replaced by text4=text1 & text2 &text3 and produces 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 Integer

 text1 = "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 string, 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 = " 2012"
 text6 = text1 + text2 + text3+text4+text5
 Label1.Text = text6
End Sub

End Class

Running the above program will produce the following screen shot.

Visual Basic 2012



8.2 String Manipulation Using VB2012 Built-in Functions

A function is similar to a normal procedure but the main purpose of the function is to accept a certain input and return a value which is passed on to the main program to finish the execution.There are numerous string manipulation functions built into Visual Basic 2012 but I will only discuss a few here and will explain the rest of them in later lessons.

8.2 (a) The Len Function

The Len function returns an integer value which is 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 format 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 VB2012. In VB2012, we need use the following format

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 program returns four rightmost characters of the phrase entered into the textbox.

The Output:

Visual Basic 2012 

*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 Visual Basic 2012.

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 .




[Lesson 7] << [CONTENTS] >> [Lesson 9]

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