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Question

I'm working on a PHP application. I need to validate that a string is useable as a currency value. I would like the following to validate:

$5.00  
5  
5.00   
£5.00  

I want the pattern to be liberal enough to accept a reasonable string. I would also like it to accept an currency symbol; however, to validate currency, it can be any character or characters because I'll ultimately store the value as a two decimal float. So, '$5.00' or 'USD 5.00' would become '5.00' when stored in the database. I'm currently using the following:

preg_match('/^[0-9]*\.?[0-9]+$/',$value)

It works for "5" or "5.00", but it does not account for the currency symbol. How do I adjust this to allow for the currency symbol?

Thank you!

EDIT: According to a comment below, it looks like my regex will allow too many decimals. Can you also help me sort out that issue?

Answer 1

To allow all currency symbols you will need to use Unicode Character Properties

\p{Sc} or \p{Currency_Symbol}: any currency sign.

Try with this one:

$value=preg_replace('/^(\p{Sc}?\d*)((\.|,)\d\d\d)?\d*$/u','$1$2',$value);

But if you are expecting the number from an input, will be better make a form where the user specify the currency from a selectable list, and just take care whether the user will only introduce numbers, that's how PAYPAL does.