Help on a Function - Not sure if it will work RESOLVED

[kenwvs]

I have written the following function, hoping to achieve that it will only allow letters, numbers, spaces, comma, and period.  I don;t want it to allow any special characters like & $ brackets *  All the shift number characters basically need to be disallowed.


[code]
<?php
function Variable($element) {                       //letters, numbers, spaces
  return !preg_match ("/[^A-z0-9,.] /", $element);//commas and periods only
}
?>
[/code]

Thanks,

Ken

[obsidian]

[quote author=kenwvs link=topic=100421.msg396284#msg396284 date=1152792317]
I have written the following function, hoping to achieve that it will only allow letters, numbers, spaces, comma, and period.  I don;t want it to allow any special characters like & $ brackets *  All the shift number characters basically need to be disallowed.


[code]
<?php
function Variable($element) {                      //letters, numbers, spaces
  return !preg_match ("/[^A-z0-9,.] /", $element);//commas and periods only
}
?>
[/code]

Thanks,

Ken
[/quote]

very close, but your space also needs to be within your brackets:
[code]
<?php
function Variable($element) {
  return preg_match('|^[a-z0-9,. ]+$|i', $element);
}
?>
[/code]

the only difference here is that i'm doing a positive match while you were doing the negative.

[kenwvs]

Positive versus Negative

Depending on whether you want it to come back true or false?

[zq29]

[quote author=kenwvs link=topic=100421.msg396289#msg396289 date=1152792928]
Positive versus Negative

Depending on whether you want it to come back true or false?
[/quote]Correct.

[obsidian]

[quote author=kenwvs link=topic=100421.msg396289#msg396289 date=1152792928]
Positive versus Negative

Depending on whether you want it to come back true or false?
[/quote]

actually, here's what i meant:

Positive:
matching to make sure that [b]every character in the string matches[/b] what you're after:
[code]
<?php
preg_match('|^[a-z0-9_,. ]+$|i', $String);
?>
[/code]

Negative:
matching any characters [b]that do not fall into your list of allowables[/b]
[code]
<?php
preg_match('|[^a-z0-9_,. ]|i', $String);
?>
[/code]

which in turn determines whether or not you want true or false to come back... for instance, if a string is TRUE for the positive match, it will be FALSE for the negative one, and vice versa. i like to match in such a way that my function itself returns exactly what i'm after. you've essentially done the same thing with your "!" before preg_match() in your original function, but i've just included that in the match itself.

hope that clears things up a bit  :P