字符串操作和拆分字符串

Question

string url = "test:app:https://test@hotmail.co.uk:Test

I need to split this up to display as follows

string first = "app";
string second = "https://test@hotmail.co.uk:Test";

i have tried the following but falls over on the last colon.

        string remove= "";
        remove= url.Replace("test:", "");
        string first= remove.Substring(remove.LastIndexOf(':') + 1);
        string second= remove.Substring(0, remove.IndexOf(':'));

Doing this i get

first = "app";
second = "Test";

When i need

first = "app";
second = "https://test@hotmail.co.uk:Test";

Answer 1

Your use of LastIndexOf is just a bit wonky.

string url = "test:app:https://test@hotmail.co.uk:Test";

string remove = url.Replace("test:", "");

string first = remove.Substring(0, remove.IndexOf(":"));
string second = remove.Substring(remove.IndexOf(first) + first.Length + 1);

First grab the app , and we can use the location of app to derive the rest of the string. Because the last index of : would be the one in :Test . We don't want the last index of : . Instead we just want whatever comes after app .

Answer 2

As everything is prefixed with test: you can use a starting position after that and then split after the first occurrance of the : character.

const int IndexOfPrefix = 5; // start position after "test:"
string url = "test:app:https://test@hotmail.co.uk:Test";
var indexOfApp = url.IndexOf(':', IndexOfPrefix);
var part1 = url.Substring(IndexOfPrefix, indexOfApp - IndexOfPrefix);
var part2 = url.Substring(indexOfApp + 1);

Console.WriteLine(part1);
Console.WriteLine(part2);

Answer 3

You can use Split(Char[], Int32) to get the desired number of elements (3 : the first unwanted part, the first expected part and the remaining) along with Skip() to remove the unwanted one :

string url = "test:app:https://test@hotmail.co.uk:Test";

var splitted = url.Split(new [] { ':' }, 3).Skip(1).ToArray();
var first = splitted[0];
var second = splitted[1];

Console.WriteLine(first);
Console.WriteLine(second);

This outputs

app
https://test@hotmail.co.uk:Test

---

Another way to do that is using regular expressions :

The pattern :(?<first>.*?):(?<second>.*) will :

• : search for the characters :
• (?<first>.*?) creates a group named first that will match any number of any character (lazy)
• : search for the characters :
• (?<second>.*) creates a group named second that will match any number of any character (greedy)

In example :

string url = "test:app:https://test@hotmail.co.uk:Test";
var pattern = ":(?<first>.*?):(?<second>.*)";
var regex = new Regex(pattern); // using System.Text.RegularExpressions;
Match match = regex.Match(url);
if (match.Success)
{
    var first = match.Groups["first"].Value;
    var second = match.Groups["second"].Value;
    Console.WriteLine(first);
    Console.WriteLine(second);
}

This outputs

app
https://test@hotmail.co.uk:Test

Answer 4

Something like this should do the trick:

public void ManipulateStrings()
{
    string url = "test:app:https://test@hotmail.co.uk:Test";
    url = url.Replace("test:", "");
    string first = url.Substring(0, url.IndexOf(':'));
    string second = url.Substring(url.IndexOf(':') + 1);

}

This basically removed test: from your string, then assigns first and second their values without creating string remove = "" for no reason.

Answer 5

you need to change the variable with name "first" to "second" and to change the variable with name "second" to "first"

This is your code:

string url = "test:app: https://test@hotmail.co.uk:Test ";

        string remove = "";
        remove = url.Replace("test:", "");
        string second = remove.Substring(0, remove.IndexOf(':'));
        string first = remove.Substring(remove.IndexOf(":") + 1);

and this is the correct code:

string url = "test:app: https://test@hotmail.co.uk:Test ";

        string remove = "";
        remove = url.Replace("test:", "");
        string first = remove.Substring(0, remove.IndexOf(':'));
        string second = remove.Substring(remove.IndexOf(":") + 1);