Reg Exp Help plz

gvanto

I am trying to get a string to contain ONLY numbers, letters and whitespaces:

if (!ereg("^{[\sA-za-z0-9]+$",} $string)) { ...

doesn't work, neither does:

if (!ereg("^{[[A-za-z0-9][\s]]+$",} $string)) { ...

i thought \s denotes a whitespace?

Any help would be much appreciated!

thanks,
Gerry
reg-exp newbie

bpat1434

Why not just do:

if(ereg("^[^a-zA-Z0-9\s]+$", $string)) {
  // It contains something else
} else {
  // Just letters, numbers, and spaces
}

The means "NOT" when inside of a span of items.

NogDog

bpat1434 wrote:
Why not just do:
if(ereg("^[^a-zA-Z0-9\s]+$", $string)) {
  // It contains something else
} else {
  // Just letters, numbers, and spaces
}
The means "NOT" when inside of a span of items.

That will only match if the entire string consists of non-alpha, non-whitespace characters, due to the start-of-string and end-of-string anchors. I think what you mean is:

if(ereg("[^a-zA-Z0-9\s]", $string))
{
  // contains an invalid character
}
else
{
  // it's OK
}

NogDog

PS: I'm not sure if ereg supports the "\s" character, so you might want to use preg_match:

if(preg_match('/[^a-z0-9\s]/i', $string))  // "i" modifier = case-insensitive
{
  // bad string
}
else
{
  // good string
}

gvanto

why the '/' in '/[^a-z0-9\s]/' ??

bradgrafelman

Because [man]preg_match/man uses the better, more effecient Perl REGEXP, which requires that the pattern be surrounded by a delimiter character and that any modifiers be placed after those delimiters (in PHP, that is).

'/' is the most common delimiter, with '@' probably being second.

madwormer2

I use # sometimes. What's the difference anyhow?

Weedpacket

The difference is if you want to use / inside the pattern. Or @. Or #.....

bradgrafelman

This:

/pattern\/expression\/etc\. with "\/" in it/

is messier than:

@pattern/expression/etc\. with "/" in it@

. Basically, if you find that the delimiter you chose appears in your pattern, you might want to switch delimiters instead of escaping it every time.

Salkcin

There´s no need for regular expression if you just want to check for alphanumeric characters (a-z A-Z 0-9), just use ctype_alnum() wich is faster.

if (ctype_alnum($string)) {

echo "Ok!";

} else {

echo "No!";

}

bpat1434

except what about white-space? ctype_alnum doesn't account for it. But a good function none-the-less.