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I am getting extension name from user to save in db in Asp Form . How i can validate that user enter extension name with .(Dot) and without .(Dot) name generate Error.

Ahsan Pervaiz
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  • you can ask user without dot and then add dot yourself? Please be aware that multiple file extensions such as `file.ext1.ext2` may cause you trouble. – mcy Sep 30 '15 at 12:26

3 Answers3

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Do you want to validate the data as the user is entering it on the form, before submitting? If so, you may be looking for a RegularExpressionValidator. See: https://msdn.microsoft.com/en-us/library/eahwtc9e(v=vs.71).aspx and http://asp.net-tutorials.com/validation/regular-expression-validator/ then use one of the Regular expressions that Webruster and Ahsan provided you.

Sample:

<asp:TextBox runat="server" id="txtExt" />
<asp:RegularExpressionValidator runat="server" 
          id="rexDot" controltovalidate="txtExt" 
          validationexpression="^[.]([a-zA-Z0-9]+)?$" 
          errormessage="Please enter a Dot!" />
Joe
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  • exactly. @Joe by using REGEX i validate my text box string and i also use the same expression as you write in comment.. Thanks for it... – Ahsan Pervaiz Oct 01 '15 at 10:40
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By using RegEx I can do it. 

Regex.Match("String to Compare" , @"^[.]([a-zA-Z0-9]+)?$")

I get user input in a string and compare it with this Validation using RegEx.

Mogsdad
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Ahsan Pervaiz
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Regular expression to validate file formats for .mp3 or .MP3 or .mpeg or .MPEG or .m3u or .M3U

Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.mp3|.MP3|.mpeg|.MPEG|.m3u|.M3U)$/;

Regular expression to validate file formats for .doc or .docx

Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.doc|.docx|.DOC|.DOCX)$/;

Regular expression to validate file formats for .txt or .TXT

Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.txt|.TXT)$/;

Regular expression to validate file formats for .jpeg or .JPEG or .gif or .GIF or .png or .PNG

Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.jpeg|.JPEG|.gif|.GIF| .png|.PNG)$/;
Krsna Kishore
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