Can some one decode what these regex do?

Posted on 2006-07-22
Medium Priority
Last Modified: 2010-03-31
I am debugging a piece of code and have a following scenario

private String REGEXP_VARIABLE_EXPANSION = "\\$\\{([\\w\\.?]*)\\}";

// How we test for booleans
private String REGEXP_BOOLEAN_VALUE = "True|T|Yes|Y";

If someone can give me an example string that will be great.  I know reverse engineering is crazy but what to do?

I am not a regex person.  But I have to work with a code.

Thanx in advance


Question by:slickdeals
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LVL 37

Accepted Solution

Harisha M G earned 672 total points
ID: 17161560

By de-escaping (?) it, the regex becomes:


So, it matches any string that has initially a $ sign, then { and a character, then any no of characters, again }

For ex,


would match, but

${ hello}, ${.hello} etc won't match.

And the second one matches only True, T, Yes or Y
LVL 26

Expert Comment

ID: 17162023
I think, it is

${Combination of alpha numeric chars with dots}
LVL 26

Assisted Solution

ksivananth earned 664 total points
ID: 17162034
for e.g.,

"${hello.123.fine} Some Text ${hello1233...} Some more here ${Not Matches.}"

it matches,

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LVL 26

Expert Comment

ID: 17162043
I feel, the "?" in the regex is irrelevant
LVL 86

Assisted Solution

CEHJ earned 664 total points
ID: 17162434
>>I feel, the "?" in the regex is irrelevant

True. Of course the regex will also match the empty var:


The other one should probably be named


LVL 26

Expert Comment

ID: 17162457
>>Of course the regex will also match the empty var:

LVL 37

Expert Comment

by:Harisha M G
ID: 17162738
${.hello} matches.. I was thinking of something else..

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