I've created a string using
String.Format(IPAddressRangeFormat, StartIP, EndIP);
Now I need to read the string back into the StartIP and EndIP objects.
What's the easiest way to do so in c#?
THanks, Li.
4 Answers
There is no easy way to do this as the reverse of a String.Format is not deterministic.
Both :
String.Format( "{0}{1}", "123", "456" )
String.Format( "{0}{1}", "12", "3456" )
gives you 123456. The machine won't just guess which one you want.
However there is a trickier way to do it, you do have regular expressions.
If you have :
String.Format ( "{0}-{1}", StartIP, EndIP);
You could use an expression :
var matches = Regex.Match ( String.Format ( "{0}-{1}", "127.0.0.1", "192.168.0.1"), "(?<startIP>.*)-(?<endIP>.*)" );
Console.WriteLine ( matches.Groups["startIP"].Value ); // 127.0.0.1
Console.WriteLine ( matches.Groups["endIP"].Value ); // 192.168.0.1
4 Comments
IAbstract
Using Regex is a bit of an over-complication in this case. why not
String.Split('-')?
Mongus Pong
You could for the example I have given. However that will only work for a few limited situations. For the general situation of reversing a Format String, this is exactly what a Regex match is designed to do. Without knowing the exact circumstances of the OP, it is the only way to handle all possibilities.
Mongus Pong
Plus, once you get over your fear of Regexes they aren't that complicated. Or rather, you can have simple regexes and you can have complex ones - depending on what you are trying to do. IMHO
(?<startIP>.*)-(?<endIP>.*) is not a complicated regex and should not take any effort for a halfway competent coder to understand.Mongus Pong
Aaargh! I didn't mean that to be directed at you. Don't take it personally. I'll get my coat...
Probably the best way to have the separate type like IPRange where you will have 2 IP's in costructor and overriden ToString(). Th parse back you probably will need to implement custom logic in lets say static Parse(string) member.
Comments
The thing you want to do called Parsing and it can't be performed by String.Format method.
Comments
Depending on your formatting for IPAddressRangeFormat, use ToString() ...then string.Split(':') ...replacing the ':' with whatever char you are using.
I would really need to see your format for IPAddressRangeFormat to provide a better answer.
IPAddressRangeFormat? There's no general solution for this problem.