提取字符串某些部分的最有效方法是什么？

Question

I have the following object:

public class Color
{
   public string RGB = "000225123";

}

I need to be able to parse out the R,G, and B components, but they may not be in that exact, however, I will know the order. So one way, it might be RGB , but another way it might be RBG .

I thought about something like this:

string G =  RGB.Substring(RGB.IndexOf('2'),3);

but here I happen to know where the G starts and ends, so I can hard-code it, which leads me to another question of what is the best way to store the order. I have thought about doing something like:

string order = "RGB";

string RGB = "000225123";

string R = RGB.Substring(order.IndexOf('R'),3);

The above works, but what about the scenario where each part can be a varied length, so R can be 2 or 3 characters for example, would that be something I store separately or would I store it within the order?

I might have a number like this:

28-34-29-000-00.0

or it could be in the order

29-34-28-000-00.0

In the above the 28 and 29 are switched and I will know this order, I will just need to know how to parse it out.

Here is a more realistic scenario and solution, but I am not sure if it is efficient enough:

string order = "TSR";

string value = "20-10-28-0000-0011";

string[] tokens = value .Split('-');

string t= tokens[order.IndexOf('T')];

string s= tokens[order.IndexOf('S')];

string r= tokens[order.IndexOf('R')];

Answer 1

I would create an interface which contains a method to parse.

Eg,

IParseColorString
{
  ColorParts Parse(String s);
}

ColorParts
{
  public string R {get;}
  public string G {get;}
  public String B {get;}
  // or if you wanted the int directly have int return type instead of string
}

Then have all the classes with the appropriate ordering derive the interface:

ParseRGB : IParseColorString
{
    public ColorParts Parse(String s)
    {
       //  parsing logic for RGB
    }
}

ParseRBG : IParseColorString
{
  public ColorParts Parse(String s)
  {
     // parsing logic for RBG
  }
}

Then use them as you like. You can even have a factory which has them as static instances

ColorParsingFactory
{
    public static IParseColorString ParseRGB {get{/* gets the RGB parser */}}
    public static IParseColorString ParseRBG {get{/* gets the RBG parser */}}
}

Answer 2

You can use a function like this to extract a component from a string:

public static int GetComponent(string data, string format, char component) {
  return Int32.Parse(new String(data.Where((c, i) => format[i] == component).ToArray()));
}

Usage:

string color = "000225123";
string format = "RRRGGGBBB";

int red = GetComponent(color, format, 'R');
int green = GetComponent(color, format, 'G');
int blue = GetComponent(color, format, 'B');

It would work for any format that you can describe that way:

string time = "2012-10-12 19:02";
string format = "YYYY MM DD hh mm";

int year = GetComponent(time, format, 'Y');
int month = GetComponent(time, format, 'M');
int day = GetComponent(time, format, 'D');
int hour = GetComponent(time, format, 'h');
int minute = GetComponent(time, format, 'm');

Answer 3

A better way to convert a color to a number is to use the ARGB-Format

Color c = Color.Aquamarine;
// Or if you have R-G-B values:  Color c = Color.FromArgb(111,222,333);
int argb = c.ToArgb(); // --> -8388652
string s = argb.ToString(); // --> "-8388652"

// Backwards
argb = Int32.Parse(s);
c = Color.FromArgb(argb);

int R = c.R;
int G = c.G;
int B = c.B;

---

UPDATE:

A simple way to store it as string by maintaining the RGB-parts would be

string s1 = "RGB;123;255;77";
string s2 = "RBG;123;77;255";

string[] parts = s1.Split(';');

int r, g, b;
switch (parts[0]) {
    case "RGB":
        r = Int32.Parse(parts[1]);
        g = Int32.Parse(parts[2]);
        b = Int32.Parse(parts[3]);
        break;
    case "RBG":
        r = Int32.Parse(parts[1]);
        b = Int32.Parse(parts[2]);
        g = Int32.Parse(parts[3]);
        break;
    default:
        r = 0;
        b = 0;
        g = 0;
        break;
}

Answer 4

Since you know the order, you can get values by using the string indexer .

Example blatantly stolen from MSDN:

string str1 = "Test";
for (int ctr = 0; ctr <= str1.Length - 1; ctr++ )
   Console.Write("{0} ", str1[ctr]);

// The example displays the following output: 
//      T e s t         

You might also want to look into System.Drawing.Color . If it's really colors you are parsing you don't even need to define your own structure.

Answer 5

If I understand correctly, there's some other service that could give you an order and an RGB string?

In that case, let's try to store types faithfully and convert data upon arrival .

public class Color{

public int R{
    get;
    set; 
    }


public int G{
    get;
    set; 
    }

public int B{
    get;
    set; 
    }

public Color(string mixedRGB, string order){
    R = Int32.Parse(mixedRGB.Substring(order.IndexOf('R'),3));
    G = Int32.Parse(mixedRGB.Substring(order.IndexOf('G'),3));
    B= Int32.Parse(mixedRGB.Substring(order.IndexOf('B'),3));
}

This will save you space if you have memory constraints and save you sanity from preventing nonsensical values assigned to your objects. (What color does the RGB string "DF)_3nAv1" make?)

You'll know what values correspond to R, G, and B because you store them seperately. IF you need to combine them frequently, you could make a function in this class to combine them.