Selecting a specific part of a string C#

I am trying to create a new string, which removes certain characters from an existing string e.g.

string path = "C:\test.txt"

so string "pathminus" wil开发者_如何学运维l take out the "C:\" e.g.

string pathminus = "test.txt"

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Use Path.GetFileName

Eg:

string pathminus = Path.GetFileName(path);

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There's so many ways that you can remove the a certain part of a string. These are a couple of ways to do it:

var path = @"C:\test.txt";
var root = @"C:\";

Using string.Remove()

var pathWithoutRoot = path.Remove(0, root.Length);
Console.WriteLine(pathWithoutRoot);                // prints test.txt

Using string.Replace()

pathWithoutRoot = path.Replace(root, "");
Console.WriteLine(pathWithoutRoot);                // prints test.txt

Using string.Substring()

pathWithoutRoot = path.Substring(root.Length);
Console.WriteLine(pathWithoutRoot);                // prints test.txt

Using Path.GetFileName()

pathWithoutRoot = Path.GetFileName(path);
Console.WriteLine(pathWithoutRoot);                // prints test.txt

You can also use Regular Expression to find and replace parts of a string, this is a little bit harder though. You can read on MSDN on how to use Regular Expressions in C#.

Here's a complete sample on how to use string.Remove(), string.Replace(), string.Substring(), Path.GetFileName() and Regex.Replace():

using System;
using System.IO;
using System.Text.RegularExpressions;

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            var path = @"C:\test.txt";
            var root = @"C:\";

            var pathWithoutRoot = path.Remove(0, root.Length);
            Console.WriteLine(pathWithoutRoot);

            pathWithoutRoot = Path.GetFileName(path);
            Console.WriteLine(pathWithoutRoot);

            pathWithoutRoot = path.Replace(root, "");
            Console.WriteLine(pathWithoutRoot);

            pathWithoutRoot = path.Substring(root.Length);
            Console.WriteLine(pathWithoutRoot);

            var pattern = "C:\\\\";
            var regex = new Regex(pattern);

            pathWithoutRoot = regex.Replace(path, "");
            Console.WriteLine(pathWithoutRoot);
        }
    }
}

It all depends on what you want to do with the string, in this case you might want to remove just C:\ but next time you might want to do other types of operations with the string, maybe remove the tail or such, then the above different methods might help you out.

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The string class offers all sorts of ways to do this.

If you want to change "C:\test.txt" to "test.txt" by removing the first three characters:

path.Substring(3);

If you want to remove "C:\" from anywhere in the string:

path.Replace("C:\", "");

Or if you specifically want the filename, regardless of how long the path is:

Path.GetFileName(path);

Depending on your intentions, there are many ways to do it. I prefer using the static class Path.

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For this specific example, I would look into the Path Class. For your example, you can just call:

string pathminus = Path.GetFileName(path);

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Have you looked at the Substring method?

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If the string is actually a file path, use the Path.GetFileName method to get the file name part of it.

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path.SubString(path.IndexOf('\'))

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You want System.Text.RegularExpressions.Regex but exactly what are you trying do here?

In its simplest form:

    [TestMethod]
    public void RemoveDriveFromPath()
    {
        string path = @"C:\test.txt";

        Assert.AreEqual("test.txt", System.Text.RegularExpressions.Regex.Replace(path, @"^[A-Z]\:\\", string.Empty));
    }

Are you just trying to get the file name of a file without the path?

If so do this instead:

    [TestMethod]
    public void GetJustFileName()
    {
        string path = @"C:\test.txt";

        var fileInfo = new FileInfo(path);

        Assert.AreEqual("test.txt", fileInfo.Name);
    }

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For more general strings, use the string.Split(inputChar), which takes a character as a parameter and splits the string into a string[] wherever that inputChar is found.

string[] stringArr = path.Split('\\'); // need double \ because \ is an escape character
// you can now concatenate any part of the string array to get what you want. 
// in this case, it's just the last piece
string pathminus = stringArr[stringArr.Length-1];