Finding Blank Lines using regular expressions
In this regular expression we are going to find out blank lines. Means we are going to search lines containing only spaces (or Whitespace) and end of line.
Regular Expression Pattern
^\s*$
A description of the regular expression:
Beginning of line or string
Whitespace, any number of repetitions
End of line or string
How It Works
This regular expression will check for blank lines contains only spaces (Whitespace). Here we are going to search Beginning of line followed by Whitespace, any number of repetitions and End of line or string.
ASP.NET
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<!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>Finding Blank Lines using regular expressions</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<span>Valid Format: enter some spaces (or Whitespace)</span><br />
<asp:TextBox id="txtInput" runat="server"></asp:TextBox><br />
<asp:RegularExpressionValidator Id="vldRejex" RunAt="server" ControlToValidate="txtInput" ErrorMessage="There is no Blank Lines" ValidationExpression="^\s*$">
</asp:RegularExpressionValidator><br />
<asp:Button Id="btnSubmit" RunAt="server" CausesValidation="True" Text="Submit"></asp:Button>
</div>
</form>
</body>
</html>
C#.NET
//use System.Text.RegularExpressions befour using this function
public bool vldRegex(string strInput)
{
//create Regular Expression Match pattern object
Regex myRegex = new Regex("^\\s*$");
//boolean variable to hold the status
bool isValid = false;
if (string.IsNullOrEmpty(strInput))
{
isValid = false;
}
else
{
isValid = myRegex.IsMatch(strInput);
}
//return the results
return isValid;
}
VB.NET
‘Imports System.Text.RegularExpressions befour using this function
Public Function vldRegex(ByVal strInput As String) As Boolean
‘create Regular Expression Match pattern object
Dim myRegex As New Regex("^\s*$")
‘boolean variable to hold the status
Dim isValid As Boolean = False
If strInput = "" Then
isValid = False
Else
isValid = myRegex.IsMatch(strInput)
End If
‘return the results
Return isValid
End Function
[...] Finding Blank Lines using regular expressions [...]