C＃String.Substring剪切出一个IpAddress和一个字符串

Question

The following code allways crashes. The input is like this: String 1 is a IpAddress ( 192.168.187.815 ) string 2 should be a Port so the whole input is 192.168.187.815,2332 . The code wich should cut out the ipAddress ( string 1 ) and the port ( string 2 ) looks like this:

Console.Write("String1,String2>");
string both = Console.ReadLine();
string string1 = both.Substring(0,both.IndexOf(","));
Console.WriteLine(string1.Length);
string string2 = both.Substring( string1.Length , both.Length - 1);
Console.WriteLine(string1);
Console.WriteLine(string2);
Console.Read();      

does anyone knows why it isn't working? I was asked for the exception so here it is. There is one little problem i am from germany and the exception is in german. i tried to translate it with google translater but i think we all know its crap. well here is the original german exception Der Index und die Länge müssen sich auf eine Position in der Zeichenfolge beziehen. Parametername: length Der Index und die Länge müssen sich auf eine Position in der Zeichenfolge beziehen. Parametername: length and here is my bad translation : the index and the length should be specified on a position in the string . parameter : Length the index and the length should be specified on a position in the string . parameter : Length i hope this make sense

Answer 1

the second parameter of String.Substring denotes the length of the substring or the number of characters that you want to pull from the string.

length
Type: System.Int32
The number of characters in the substring.

Your solution would be to subtract the start index from the both.Length . This way you get the number of characters between the , and the end of the entire string both

string string2 = both.Substring(string1.Length+1, both.Length - 1-string1.Length);

Also note that you should take the start index +1 if you want to avoid the , in your string/portnumber.

Another possibility would be to use the String.Split method to split at the separator , . It will return an string[] and you can easily assign the values:

string both = "192.168.187.815,2332";
string[] splitted = both.Split(new char[] {','}, StringSplitOptions.RemoveEmptyEntries);
string string1 = splitted[0];
string string2 = splitted[1];


Console.WriteLine(string1);
Console.WriteLine(string2);

Disclaimer: this solution implies strongly that you really have an input string in the format "something,someting" otherwise you might run into an index out of bounds. You should check the length of the array splitted before accessing hard coded indexes!

Answer 2

It's clear that the separator is , then why are you complicating things by using Substring why not proceed with Split like the following:

    string[] inputParams= both.Split(',');
    string ipAddress = inputParams[0];
    string portNumber =inputParams[1];

• Actually the second parameter of the String.Substring() method represents the number of characters(not the last index as you thought).

• If you again wish to proceed with Substring the you can try like the following:

   string ipAddress = both.Substring(0,both.IndexOf(",")); string portNumber =both.Substring(both.IndexOf(",")+1) 

  But still the first one is the best for this situation