How does '?' in regular expression works?

[Haneef]

Hi,

I found regular expression as follows ione of teh VI.

Regular expression as: [-]?[.]?[0-9]+[.]?[0-9]*

The output is, it will extact the number from sentance.

Can any oneexplain me with an example (using multiple '?') please how does '?' works?

Many Thanks

Haneef

[TCPlomp]

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@Haneef wrote:

Hi,

I found regular expression as follows ione of teh VI.

Regular expression as: [-]?[.]?[0-9]+[.]?[0-9]*

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From the help:

?          Marks part of a pattern as one that can appear zero or one time in the input. For example, be? matches be in believe, be in bee, be in beep, and b in bat..

So your RegEx consist of the following parts:

[-]?    0 or 1 times the '-' sign

[.]?    0 or 1 times the '.' sign

[0-9]+ 1 or more numbers (0-9)

[.]?    0 or 1 times the '.' sign

[0-9]* 0 or more numbers (0-9)

Note that this regex doesn't deal with 'european' decimals using a ',' as decimal character.

Ton