VB.NET ASP.NET IndexOf() Source Code Syntax Example

Posted by on Sunday, February 20, 2011 · Leave a Comment 

IndexOf Example Syntax VB.NET ASP.NET | IndexOf | Source Code

Summary: – Illustrates using with in VB.NET ASP.NET.

 *** 1. Download Source Code *** 
VB.NET Syntax StringManipulation IndexOf download Download Source Code for All VB ASP.NET Examples in One Project – source code for hundreds of VB.NET ASP.NET examples neatly organized in a single project.

 *** 2. IndexOf Syntax *** 


Purpose:
Returns an integer that represents the position of the first occurrence of the
specified number of characters. If you specify startIndex, that specifies
where to start looking. If you specify count, that specifies how many characters to
to search past start. If the string is not found, this method returns -1


Syntax:
string.IndexOf(matchstring[, startIndex][,count])

Parameters Description
string Required – string to be searched
matchstring Required – string that you are looking
for in parameter1
startIndex Optional. specifies where to start looking. Zero-based.
count Optional. specifies how many characters to
to search past start.

Result Data Type Description
integer Returns an integer that represents the position of the first
occurrence of the specified number of characters. If the string is not found,
this method returns -1. The integer returned is a zero-based index so the first
position is represented by 0 instead of 1.


 *** 3. IndexOf – Quick Example *** 
Dim strIndexOfExample As String = “This is a test string”
TextBox1.Text = strIndexOfExample.IndexOf(“is”) ‘Returns 2
TextBox2.Text = strIndexOfExample.IndexOf(“xyz”) ‘Returns -1 (not found)

 *** 4. IndexOf – Full Example *** 

IndexOf Example Output Screenshot


VB.NET Syntax StringManipulation IndexOf screenshot


Step 1: Click on Visual Basic to Cut-n-paste code into IndexOf.aspx.vb

Imports System
Imports System.IO
Imports System.Data
 
 
' This example is from http://idealprogrammer.com
' It shows how you can use IndexOf syntax in VB.NET ASP.NET
'****************************************************************************************
' Purpose:  Returns an integer that represents the position of the first occurrence of the
' specified number of characters. If you specify startIndex, that specifies
' where to start looking. If you specify count, that specifies how many characters to 
' to search past start. If the string is not found, this method returns -1
'
' Syntax: 	string.IndexOf(matchstring[, startIndex][,count])
'
' Parameter1: string - Required - string to be searched
'
' Parameter2: matchstring - Required - string that you are looking 
' for in parameter1
'
' Parameter3: startIndex - Optional. specifies where to start looking. Zero-based.
'
' Parameter4: count - Optional. specifies how many characters to 
' to search past start.
'
' Result: integer - Returns an integer that represents the position of the first 
' occurrence of the specified number of characters. If the string is not found, 
' this method returns -1.  The integer returned is a zero-based index so the first
' position is represented by 0 instead of 1.
'
' Quick Example:    Dim strIndexOfExample As String = "This is a test string"
' TextBox1.Text = strIndexOfExample.IndexOf("is") 'Returns 2
' TextBox2.Text = strIndexOfExample.IndexOf("xyz") 'Returns -1 (not found)
'
' 
'****************************************************************************************
Partial Class _IndexOf
    Inherits System.Web.UI.Page
 
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
 
        Label1.Text = "Example #1: strIndexOfExample.IndexOf(""is"").ToString() "
 
        Dim strIndexOfExample As String = "This is a test string"
 
        TextBox1.Text = strIndexOfExample.IndexOf("is").ToString() 'Returns 2
 
        Label2.Text = "Example #2: strIndexOfExample.IndexOf(""xyz"").ToString() "
        TextBox2.Text = strIndexOfExample.IndexOf("xyz").ToString() 'Returns -1 (not found)
 
    End Sub
End Class

Step 2: Click on XML to Cut-n-paste code into IndexOf.aspx

< %@ Page Language="VB" AutoEventWireup="false" CodeFile="IndexOf.aspx.vb" Inherits="_IndexOf" %>
 
< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h1><asp:label ID="Label1" runat="server" Text="Label"></asp:label> </h1>
         <asp:textbox ID="TextBox1" runat="server"></asp:textbox><br />
          <h1><asp:label ID="Label2" runat="server" Text="Label"></asp:label> </h1>
         <asp:textbox ID="TextBox2" runat="server"></asp:textbox><br />
          <h1><asp:label ID="Label3" runat="server" Text="Label"></asp:label> </h1>
         <asp:textbox ID="TextBox3" runat="server"></asp:textbox><br />
 
 
 
    </div>
    </form>
</body>
</html>

Prerequistes:

  1. Install Visual Web Developer 2010
  2. Install SQL Server Express
  3. Download Northwind and Pubs Databases
  4. Attach Northwind Database to Databases in Sql Express
  5. Attach pubs Database to Databases in Sql Express

Notes:

  • You can build your own library of syntax examples by using same web site over and over and just add new web forms to it.

Instructions:

VB.NET ASP.NET Syntax StringManipulation IndexOf
  1. Use Visual Web Developer 2010
  2. Create new web site;
    • Click File/New Web Site
    • Select ASP.NET Website Template
    • Select Visual Basic for Language
    • name of Web Site could be VBNET_ASPNET_Syntax.
  3. Add New folder named “StringManipulation”
    • Right-click project name in solution explorer;
    • add new folder;
    • name of folder could be: StringManipulation
  4. Add Web Form Named IndexOf to StringManipulation folder
    • Right-click StringManipulation folder;
    • add new item;
    • Select Web Form
    • Check place code behind in separate file
    • Web Form name could be IndexOf
  5. Click on Visual Basic in step 1 at the top of this page to copy code into code-behind IndexOf.aspx.vb
  6. Click on XML in step 2 above to copy code into web form IndexOf.aspx
  7. Right-click on IndexOf.aspx in solution explorer and select view in browser

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