Regexp to pull numerics only

I'm using regexp to pull a version number from a text file:

      returned = string(regexp (filetext, '(?<=Version_String )[A-Z]*\d*.\d*.\d*.\d*', 'match'))

This returns a string

"YZ1.1.2.3"

which is good.

When I try and extract just the numbers and decimal point from this string with

version = regexp (returned, '\d*.\d*.\d*.\d*', 'match')

I get:

version = 1x2 string array "YZ1.1"  ".2.3"

which is not what I was expecting. I was hoping for 1.1.2.3

Can someone explain why this is returned and possibly how to fix it please?

edit: Apologies to all, I missed the decimal points after the \d, I have corrected. I wrote this on my phone in my lunch break!

[Stephen23]

I don't see anything in any of your regular expressions that would match the points.

When I test your first example, I do not get the result that you have shown us:

>> S = 'A B C Version_String YZ1.1.2.3 X Y Z';
>> regexp(S, '(?<=Version_String )[A-Z]*\d*\d*\d*\d*', 'match')
ans = 
    'YZ1'

which is exactly what I would expect (as the matching fails at the first dot character).

Answer 1

[Guillaume]

• \d*\d*\d*\d* is exactly the same as \d*, match 0 or more digits. It probably would be better as \d+, match 1 or more digits
• That regular expression cannot return anything with letters or dots in it, so it's clearly not what you are using.

[Stephen]

Yes, thank you, disregarding the errors I made when writing up the question, the problem was using * instead of +