preg_replace - strip unwanted characters from string to return numeric value

Question

I hate regular expressions and I was hoping someone could help with a regualar expression to be used with preg_replace.

I want to strip unwanted characers from a string to return just a numeric value using preg_replace.

The string format could be as follows:

SOME TEXT £100

£100 SOME TEXT

SOME TEXT 100 SOME TEXT

Many thanks

Answer 1

$NumericVal = preg_replace("/[^0-9]/","",$TextVariable);

the ^ inside the [ ] means anything except the following

Edit removed superfluous +