C# Extract Decimal number with out period

Question

I need to extract a decimal number from string. Currently I am using this regex to find a decimal number but it need a proper decimal value.

 var value = Regex.Match(formula, @"(?n)\d+(\.(?<decimal>\d+))?");
            return value.Groups["decimal"].Success ? int.Parse(value.Groups["decimal"].Value) : 0;

if I write 2.1 it gives me 1 but when write .1 it doesn't evaluate that string.

I need to extract a decimal number from these string with one regex

2.1 = 1
.5 = 5
SMA(21).6 = 6

How to do it?

Possible duplicate of [Get the decimal part from a double](http://stackoverflow.com/questions/13038482/get-the-decimal-part-from-a-double) — Jeric Cruz, Nov 04 '16 at 11:36
Why is `SMA(21).6` a number? Are there any other peculiar test cases? — Wiktor Stribiżew, Nov 04 '16 at 11:36
actually, I just need decimal number only. which is .6 in this case. I need only 6 with out period. — Haseeb Khan, Nov 04 '16 at 11:39
Yes... Try a naive [`@"\.(?\d+)"`](http://regexstorm.net/tester?p=%5c.%28%5cd%2b%29&i=2.1+%3d+1%0d%0a.5+%3d+5%0d%0aSMA%2821%29.6+%3d+6), or a more complex [`@"(?n)(\([A-Z]+\)|\d|\B)\.(?\d+)"`](http://regexstorm.net/tester?p=%28%3fn%29%28%5c%28%5bA-Z%5d%2b%5c%29%7c%5cd%7c%5cB%29%5c.%28%3f%3cdecimal%3e%5cd%2b%29&i=2.1+%3d+1%0d%0a.5+%3d+5%0d%0aSMA%2821%29.6+%3d+6) — Wiktor Stribiżew, Nov 04 '16 at 11:39
and yes there are many test cases in which I follow the same pattern of writing string. Like SMA(21).6, TMF(21).5, EMA(29).45 etc — Haseeb Khan, Nov 04 '16 at 11:40
`var res = Regex.Match(formula, @"\.(\d+)").Groups[1].Value;` or `var res = Regex.Match(formula, @"\.(?\d+)").Groups["decimal"].Value;` — Wiktor Stribiżew, Nov 04 '16 at 11:42
@WiktorStribiżew thanks very much its exactly what I needed — Haseeb Khan, Nov 04 '16 at 14:03

score 1 · Accepted Answer · answered Nov 04 '16 at 14:07

1

It seems you just want to extract 1 or more digits after a dot. You may use a simple \.(\d+) regex that matches a literal dot and then matches and captures 1 or more digits into Group 1.

Use

var m = Regex.Match(formula, @"\.(\d+)");
var res = string.Empty;
if (m.Success)
{ 
    res = m.Groups[1].Value;
}

See the regex demo

answered Nov 04 '16 at 14:07

Wiktor Stribiżew

607,720
39
448
563

I have another situation in which I need to extract string followed which sometimes contain a decimal number and sometimes not. I have two string like this MACD(C,26,12,9) SMA(C,26,12,9).1 when i use this regex (MACD)\([^()]*\)\.(?\d+) its only select one with decimal number but I want to select both. What I am doing wrong here? – Haseeb Khan Nov 04 '16 at 14:36
You need to be specific. If you need to specify exact context (match `.` after `MACD`, `SMA` (Forex terms, I know)), you need to use alternation: [`@"(?n)\b(MACD|SMA)\([^()]*\)\.(?\d+)"`](http://regexstorm.net/tester?p=%5cb%28MACD%7cSMA%29%5c%28%5b%5e%28%29%5d*%5c%29%5c.%28%3f%3cdecimal%3e%5cd%2b%29&i=MACD%28C%2c26%2c12%2c9%29.12+SMA%28C%2c26%2c12%2c9%29.1&o=n). – Wiktor Stribiżew Nov 04 '16 at 14:39
its only select SMA string but not MACD string. Do I need to use OR condition to select both? – Haseeb Khan Nov 04 '16 at 14:44
Your `MACD(C,26,12,9)` has no period. How come you want it to be matched? – Wiktor Stribiżew Nov 04 '16 at 14:46
that's what I mentioned that I wanted to select both sometime string have period and sometimes not – Haseeb Khan Nov 04 '16 at 15:16
period is optional – Haseeb Khan Nov 04 '16 at 15:18
Then use `\b(MACD|SMA)\([^()]*\)(\.(?\d+))?` – Wiktor Stribiżew Nov 04 '16 at 15:31

C# Extract Decimal number with out period

1 Answers1