[SOLVED] if statement help: identifying if the user has placed invalid characters

[HoTDaWg]

what would the code look like if you wanted to tell the user their info they submitted into a form had invalid characters? would you use ereg?

 

thanks

 

HoTDaWg

[donynam]

use regular expression.

 

Please check this page http://my2.php.net/manual/en/function.preg-match.php

 

or you can write some classes or functions to handle this situation.

[obsidian]

would you use ereg?

 

As donynam suggests, I would use preg as well.

[HoTDaWg]

any idea why this jumps directly to the string acceptable instance?

 

<?php

$username ="ABCDEFGhjikl(*&*%$*())*^%$#!mnop102022\/.,[]]]]]]";
if (preg_match("[a-zA-Z0-9]",$username)){
echo "Unacceptable characters are in this string";
}else{
echo "string acceptable:S \r \n {$username} ";
}
?>

again, all i want to do is identify if the variable contains specific characters.

 

[obsidian]

any idea why this jumps directly to the string acceptable instance?

 

As you have it, you are matching any string that contains at least one alphanumeric character. If you are trying to find any strings that contain only alphanumeric characters, you'll want to do something like this:

<?php
$username ="ABCDEFGhjikl(*&*%$*())*^%$#!mnop102022\/.,[]]]]]]";

// negative match
if (preg_match('|[^a-z\d]|i', $username)) {
  // not valid
}

// positive match
if (preg_match('|^[a-z\d]+\z|i', $username)) {
  // valid match
}
?>

[HoTDaWg]

at the risk of sounding noobish, i am curious to know why are the specific characters |[^a-z\d]|i placed within the single quotes?

[obsidian]

at the risk of sounding noobish, i am curious to know why are the specific characters |[^a-z\d]|i placed within the single quotes?

 

[pre]

"|"  == my choice of delimiter (opening)

"["  == begin a character set

"^"  == declares a negative search (match anything NOT part of this set)

"a-z" == alpha characters

"\d"  == digits

"]"  == close character set

"|"  == my choice of delimiter (closing)

"i"  == declares a case insensitive search

[/pre]

 

Hope this helps

[HoTDaWg]

very much so , thanks a lot obsidian