Simple Numeric Regex Match

Question

Hi I'm having an issue doing a simple numeric match, what am I doing wrong:

Criteria:

1) Always anchor to start
2) Always Numeric 6-7 digits
3) Always Followed by _ (underscore)

Sample: (want to match everything before LoremIpsum)

1212384_LoremIpsum...
1266625_LoremIpsum...
234233_LoremIpsum...
2348199_LoremIpsum...

I have tried a couple of things: (Does not Match)

^[\d]{6-7}_
^[0-9]{6-7}_

If I do:

^[\d]{6}_
^[0-9]{7}_

I get matches, why can't I do variable length in this expression ? What am I missing here ?

Thanks !

Answer 1

The correct syntax is with a comma:

{6,7}

Not:

{6-7}

Also, you don't have to put the \\d in brackets:

^\d{6,7}_