Using PHP to avoid meaningless text in form fields

I tried to make php form script, which process data submitted by the user, but I want to find, how can I allow only meaning full text in those form fields like "Honey" and other real meaning full user names

I mean, sometimes, user may enter its name like: assalhdjsdyoeorsdhs. although text entered is within allowed text length, but its not a name at all, so how to disallow such non-sense usern开发者_开发问答ames, which created for just to submit an entry like in comments page also.

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From a list of existing usernames, create a Markov chain on the likelyhood of the next letter. E.g. when you encounter the letter D, it is likely that the next letter is an E but it is nog likely that is is an M.

Then, check each new username against this Markov chain to determine the likelyhood that it is a normal username.

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I think the only sure way of doing this is to have human intervention in the approval process for new users.

I don't know if that's an option for you, but a software based system is sure to be more trouble than just ignoring the problem.

I had a similar problem on a bulletin board I run, in the end I appointed some trusted users as admins and all new users had to be authorised manually. The problem was solved, but we don't have a high number of new users.

Edit

Another option I have just thought of is to use one of the methods suggested here to flag a user name for human attention.

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you have to create database which will keep the relevant names.from where you can check every entry.it is not possible to prevent users for submitting words like "agasdffdssd"

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You could download a plain-text dictionary, and then check if the registered name is in that dictionary. Here is a sample website with dictionaries, including the English one: http://www.winedt.org/Dict/

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You must first define what you consider "meaningful". Is "Demla" meaningful? It might not be in the dictionary (at least not in the Dutch one :) ), so you can't use that. You could parse for certain word-shapes, but you would have to take all the false positives or false negatives for granted. It won't be 100% at all. Is Asd a name? or the beginning of ASDF?

You could start something with a Markov chain, but you'd have a hard time getting it right and also explaining this to your users on false positives...

I'd filter problematic entries on other fields, and dissallow some basic stuff (like letters).

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http://www.haykranen.nl/2008/09/21/markov/ may this useful. it has markov generator with some source to download. try it.