Filter string

[birbal]

i want to customize that in my register page..only a-z,1-0 can be stored...how to filter the input from user. if user input other than a-z or 1-0 ..it will return a error..will the filter regexp work on it..give some idea on it.

[justsomeguy]

You can use preg_match to find characters that do (or don't) match your pattern.

[birbal]

You can use preg_match to find characters that do (or don't) match your pattern.

ok can you please give some code and ilaborate it or give me any link for preg_match tutoriali find in php.net syt bt..it i am not getting all the things like pattern,delimeter and use of it..

[justsomeguy]

There's a fair amount to know about regular expressions, but this describes the pattern syntax that PHP uses:http://www.php.net/manual/en/reference.pcr...tern.syntax.phpThis site also has a lot of information:http://www.regular-expressions.info/It sounds like you want to use character classes, so something like this would match any lowercase letter or digit:[a-z0-9]

[jeffman]

It would be more useful to add a NOT operator to the character class:[^a-z0-9]Pass that and your string to preg_match, and if you get a match, even 1 match, then the string fails.

[birbal]

that link was good but i felt this is little wired thing. it is more complex than i thought..:)i figured out a code for me. please correct me. i am not sure it will work or notobjective:1) all will be lowercase(a-z) or numaric(0-9) and underscore,dash,fullstop. other will will not be accepted.2) minimum 3 letters maximum 10 letters.3) input will be case sensetive.4) it will seacrh entire string and ensure there is not any other letter than i described in 1code:

if(preg_match("/[^a-z0-9_.-]{3,10}/",$inputstring)){//wrong word}else{//right word}

1)what is diffrenece beetwin preg_match() and preg_match_all()?

[jeffman]

I see I have confused you. This code will tell you if any character in the string is not a valid character. The match process stops as soon as one bad character is found.

if(preg_match("/[^a-z0-9_.-]/",$inputstring)){//wrong word}else{//right word}

Adding the quantifier {3,10} to this kind of match will not work, because the test looks for characters that do not match, not strings that do match. I think you did not mention the length requirements before. With a few changes, you can have that too. Try this regex instead:/^[a-z0-9_.-]{3,10}$/This expression wants to match a string between 3-10 characters long, containing only [a-z0-9_.-], and the beginning of the match must be the beginning of the string, and the end of the match must be the end of the string.The ^ and $ do that last part, which is important. Without it, the following would be a match:!@#(HELLO.1234****Because HELLO.1234 fits the pattern. When we add the ^ and $ controls, the extra characters cause the string to fail. But this by itself will still match:HELLO.1234Be careful about the placement of the ^ character. It means different things when it is inside [brackets] and when it is outside them. For this new regex, it must come outside the brackets.