PowerShell regex and e.164 telephone numbers -

i'm looking telephone numbers have 12 or 13 digits.

the following 2 regex work:

ps c:\data\umcp> $bla = [regex]'^(\+[3][9])?([0-9]\d{9})$' ps c:\data\umcp> $twelv -match $bla true ps c:\data\umcp> $bla = [regex]'^(\+[3][9])?([0-9]\d{10})$' ps c:\data\umcp> $thirt -match $bla true 

but

ps c:\data\umcp> $bla = [regex]'^(\+[3][9])?([0-9]\d{9} | ^\+[3][9])?([0-9]\d{10})$' ps c:\data\umcp> $thirt -match $bla true ps c:\data\umcp> $twelv -match $bla false 

how should use | or?

you have whitespaces around pipe, , whitespace matters. make whitespace (like this, e.g.) "formatting whitespace", add (?x) ignorepatternwhitespace inline modifier start of pattern.

also, should careful unescaped parentheses, make groups , must paired.

your fixed pattern like

'^(?:(?:\+[3][9])?[0-9]\d{9}|(?:\+[3][9])?[0-9]\d{10})$'   |   |--opt.gr.-|          | |-opt.gr.--|           |   |---------- branch 1------|-------- branch 2-------| 

see how groups created: outer parentheses create group ^ , $ applied both alternative branches, , inner ones used form optional group (with ? quantifier after them).

if have string matching pattern:

• an optional +39 @ start
• 10 or 11 digits end of string

use

^(?:\+39)?[0-9]{10,11}$ 

see regex demo