Get specific characters from string

Question

I have many string format as : RGB:ABC.XX,DEF.XX,GHI.XX where ABCDEFGHI are numbers.

I need to extract the R (ABC), G (DEF), B (GHI) from that String The problem is that the string can take many form like

RGB:AB.XX,DE.XX,GHI.XX
RGB:ABC.XX,DE.XX,GH.XX
RGB:ABC.XXX,DE.XX,GH.XX
RGB:ABC.XXX,DE.XX,GH.XX
...
...
...

So as you can see, there's many thing to consider to extract this rbg from that string.

I tried to use LINQ but that will be a mess I think (That is only for the first 'R' (red)):

rgb[0] = new String(rgbName.SkipWhile(x => char.IsLetter(x) || x == ':').TakeWhile(x => char.IsNumber(x)).ToArray());

Is there a more efficient way to do that? Maybe regex can do that thing but i'm not an expert. Any help will be appreciate.

Thanks.

Answer 1

You can try this regex

.*?(?<R>\d+).*?(?<G>\d+).*?(?<B>\d+)

You can access the group like this

 Regex.Match(input,regex).Groups["R"].Value;//Red value

Answer 2

Luckily, only a limited degree of regex expertship is required for this, so give it a try:

What you need to know:

• () encloses a capturing group - from the complete match, you will be able to extract those as single strings
• [] encloses a set of allowed characters
• \\. is a fullstop (escaped, because it otherwise has a special meaning outside of [] in C#'s regex implementation)
• \\ in general is used for escaping special characters
• + means one or more times of the preceding sub-expression
• ^ and $ denote the beginning and the end of the string, respectively

With that in mind, you can try the following regular expression:

^RGB\:([0-9]+)\.[0-9]+\,([0-9]+)\.[0-9]+\,([0-9]+)\.[0-9]+$

Use this to invoke the Match method of the Regex class .

The resulting Match instance has a Groups property which should contain four elements:

• the complete matched string
• the R part
• the G part
• the B part

Every such item is an instance of the Group class . Use its Value property to retrieve the matched string.

Answer 3

Yep, regex will be ideal but until you learn that, work with what you (and an average developer) know.

Break the problem into smaller ones
- Remove the "RGB:" part
- Split the string into an array of strings with delimiter the comma (,)
- Get the values from each string in the array

The best solution is not the one with the fewer lines of code. It's the one that can be understood by any developer who will later has to read your code.