Regex subtract amount if the number is bigger than

Question

I'm looking for a way to subtract a fixed amount if the number is bigger than specified value - using regex

e.g.

If the number is bigger than 10000 I want to subtract 5000, so it should look like:

175 -> 175
7831 -> 7831
12091 -> 7091

Probably better to use some form of coded non-regex logic. Regex is not for everything... — Alderath, Jan 28 '13 at 10:15
You can't do math operations with regular expressions. Your solution is way easier than regexes anyway `if (value > 10000) value =- 5000;` — m0skit0, Jan 28 '13 at 10:17
I think C#, I use Visual Web Ripper software and I'm trying to create a content transformation script. — user2016412, Jan 28 '13 at 10:19
@Qtax can you show me an example of math operation with regex? — m0skit0, Jan 28 '13 at 10:33
@m0skit0 http://stackoverflow.com/questions/5245087/math-operations-in-regex example there, but works only in perl (perl evaluates the expression, not regex itself). — Destrictor, Jan 28 '13 at 10:56
@m0skit0, example: Add 1 to all integers `2 > x >= 0`: `s/\b1\b/2/g; s/\b0\b/1/g;`. In a [unary numeral system](http://en.wikipedia.org/wiki/Unary_numeral_system) you can add one just by using `s/^/1/`. In binary you could use an expression like `s/(?:0|\b(?=1)|(\G1))(?=1*$)/$1?0:1/ge`. I had to use `/e` here, but there could be a workaround using multiple expressions. (Perl syntax.) — Qtax, Jan 28 '13 at 11:08
@Qtax: cool examples :) Although they don't work for decimal system, which is the point of the question. — m0skit0, Jan 28 '13 at 11:21

score 2 · Answer 1 · edited Jan 28 '13 at 11:06

2

Regex is used for pattern matching, replacing text.

You cannot use regex to do mathematical operations.

At max, in C# you can do this:

String s = Regex.Replace(input, @"\b\d{5,}\b", m => (int.Parse(m.Value)-5000).ToString());

So,

44 10000 15000 1 100

would become

44 5000 10000 1 100

edited Jan 28 '13 at 11:06

nhahtdh

answered Jan 28 '13 at 10:50

Anirudha

1 Answers1