CODEWITHSUNDEEP
c#.net
user3314399
user3314399

Reputation: 325

Substring until end of the character

How can I substring a character until the end of the text which the length of the string always changes? I need to get everything after the ABC The samples are:

ABC123
ABC13245
ABC123456
ABC1

Upvotes: 6

Views: 27709

Answers (2)

Shaun Luttin
Shaun Luttin

Reputation: 141752

Answer

var startIndex = "ABC".Length;
var a = "ABC123".Substring(startIndex); // 123
var b = "ABC13245".Substring(startIndex); // 13245
var c = "ABC123456".Substring(startIndex); // 123456
car d = "ABC1".Substring(startIndex); // 1

Remarks

With Substring() - Faster

string.Substring(int startIndex) returns all the characters after startIndex. Here it is as a method you can use.

public static string SubstringAfter(string s, string after)
{
    return s.Substring(after.Length);
}

With Remove() - Slightly Slower

string.Remove(int start, int count) returns a new string after removing count characters beginning with the character at index start. 

public static string SubstringAfter(string s, string after)
{
    return s.Remove(0, after.Length);
}

With Substring() and IndexOf() - Slower Still

If your string started with something other than ABC, and if you wanted to get everything after ABC, then, as Greg rightly answered, you would use IndexOf().

var s = "123ABC456";
var result = s.Substring(s.IndexOf("ABC") + "ABC".Length)); // 456

Proof

Here's a demo, which also shows which is fastest.

using System;
public class Program
{
    public static void Main()
    {
        var result = "ABC123".Substring("ABC".Length);
        Console.WriteLine(result);
        Console.WriteLine("---");

        Test(SubstringAfter_Remove);
        Test(SubstringAfter_Substring);
        Test(SubstringAfter_SubstringWithIndexOf);
    }

    public static void Test(Func<string, string, string> f)
    {
        var array = 
            new string[] { "ABC123", "ABC13245", "ABC123456", "ABC1" };

        var sw = new System.Diagnostics.Stopwatch();
        sw.Start();
        foreach(var s in array) {
            Console.WriteLine(f.Invoke(s, "ABC"));
        }
        sw.Stop();
        Console.WriteLine(f.Method.Name + " : " + sw.ElapsedTicks + " ticks.");
        Console.WriteLine("---");
    }

    public static string SubstringAfter_Remove(string s, string after)
    {
        return s.Remove(0, after.Length);
    }

    public static string SubstringAfter_Substring(string s, string after)
    {
        return s.Substring(after.Length);       
    }

    public static string SubstringAfter_SubstringWithIndexOf(string s, string after)
    {
        return s.Substring(s.IndexOf(after) + after.Length);        
    }    
}

Output

123
---
123
13245
123456
1
SubstringAfter_Remove : 2616 ticks.
---
123
13245
123456
1
SubstringAfter_Substring : 2210 ticks.
---
123
13245
123456
1
SubstringAfter_SubstringWithIndexOf : 2748 ticks.
---

Upvotes: 11

Greg Ennis
Greg Ennis

Reputation: 15381

string search = "ABC"; 
string result = input.Substring(input.IndexOf(search) + search.Length);

Upvotes: 18

Related Questions