Regex pattern not being detected properly in C#

Question

I have a specific pattern I want to follow but the extraction process is not working as expected. I assume the pattern I developed is not correct, but I can't find the issue in it.

I have the string string test1 = "R1 0.1uF" and the pattern

"(?<des>^[a-zA-Z]+)|(?<number>\d+\s+)|(?<val>[0-9]*.?[0-9]+)|(?<units>[^,]*)";

I want it to be extracted as follows:

des: R

number: 1

val: 0.1

units: uF

Currently, des is working properly and it's finding R but the others return an empty string.

Here's my code

const string pattern = @"(?<des>^[a-zA-Z]+)|(?<number>\d+\s+)|(?<val>[0-9]*.?[0-9]+)|(?<units>[^,]*)";

string test1 = "R1 0.1uF";

Regex r = new Regex(pattern, RegexOptions.Compiled);

Match m = r.Match(test1);
string des = m.Groups["des"].Value;
string number = m.Groups["number"].Value;
string val = m.Groups["val"].Value;
string units = m.Groups["units"].Value;

Answer 1

Two comments:

1. Remove all the |s because you don't want to match des OR number OR val OR units but des followed by number followed by val followed by units
2. Escape the dot: \. because you want to match a dot, not some random character.

So, your regex becomes

(?<des>^[a-zA-Z]+)(?<number>\d+\s+)(?<val>[0-9]*\.?[0-9]+)(?<units>[^,]*)

Look at regex101

Some little improvements, if I may:

• Move the caret ^ to the front. It doesn't belong in the first group.
• Do not capture the space(s) in the group number.

Like this:

^(?<des>[a-zA-Z]+)(?:(?<number>\d+)\s+)(?<val>[0-9]*\.?[0-9]+)(?<units>[^,]*)

See regex101