Check IMG

[Guest]

Hi all,
Some web sites (for example mySpace) had in the registration form an image
with alfanumeric chars... used to check the submit
Could you say me ... how can I realize this ??
Or could you give me some link where I can read this ??
Thanks in advance.
//HH

 

[Laurent Bugnion]

Hi,

Hi all,
Some web sites (for example mySpace) had in the registration form an image
with alfanumeric chars... used to check the submit
Could you say me ... how can I realize this ??
Or could you give me some link where I can read this ??
Thanks in advance.
//HH

It's fairly easy. Put all these images in a folder. The image name
should carry the letters/digits sequence (for example, if the image
displays abc123, the image name could be abc123.gif) Then use
server-side code to randomly select one image from this folder. Save the
image name in a session variable. When the user sends the request,
compare what he entered to the variable saved in the session.

Note that these images have a huge inconvenient: They make pages
unaccessible for blind people. Usually web browsers for "visually
impaired" people use the title of the alt attribute to read the image's
description out loud, but obviously you cannot use this in your rendered
HTML code. So you need to provide your users with an alternative solution.

HTH,
Laurent

 

[mc]

visit here (http://www.codeproject.com/aspnet/CaptchaImage.asp) for more
info on how to dynamically create such images. It's not the most complex
of Captcha algorithms but it seems to keep the bots out on my site.

For an example of it in my application visit
http://www.mikecaddy.co.uk/reds/LogComment.aspx

Regards


mc

 

[Guest]

Hi all,
Really thanks for your help

visit here (http://www.codeproject.com/aspnet/CaptchaImage.asp) for more
info on how to dynamically create such images. It's not the most complex
of Captcha algorithms but it seems to keep the bots out on my site.

For an example of it in my application visit
http://www.mikecaddy.co.uk/reds/LogComment.aspx

Regards


mc