Substring in C#

Question

I have string "10-1283-01" the length going to be same , i want to check is that string like "10-xxxx-0x" only want first 3 character like "10-" and last but one two character like "-0".

So I am diving/Substring something like below. for first3 its giving me required string but for lastPart its giving me ArgumentOutOfRangeException.

Please let me know how i will get -0 string? Thanks in Advance

 string partnoveri = lpartno.Text; string first3=partnoveri.Substring(0, 3); string lastPart = partnoveri.Substring(partnoveri.IndexOf("-0"),partnoveri.Length-1);

if ((partnoveri.Substring(0,3)=="10-"&&(partnoveri .substring(7,2)=="-0")) then valid else not valid — Shon
– Shon, Commented May 20, 2016 at 23:35

dfdsfdsfsdf · Accepted Answer · 2016-05-20 21:53:05Z

1

why dont you use regular expression?

using System; using System.Threading; using System.Threading.Tasks; using System.Linq; using System.Collections.Generic; using Newtonsoft; using Newtonsoft.Json; using Newtonsoft.Json.Serialization; using Newtonsoft.Json.Linq; using System.Text.RegularExpressions; class Program { static void Main(string[] args) { try { var pattern = "[0-9]{2}-[0-9]{4}-[0-9]{2}"; var input = "10-1283-01"; var matches = Regex.Matches(input, pattern); if(Regex.IsMatch(input, pattern)) { Console.WriteLine("MATCH"); } } catch (Exception ex) { Console.WriteLine(ex.Message); } } }

answered May 20, 2016 at 21:53

dfdsfdsfsdf

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5 Comments

Andrew Morton Over a year ago

The OP gave a criterion for which the regex pattern would be "^10-[0-9]{4}-0[0-9]$" (assuming the x is intended to be [0-9]).

dfdsfdsfsdf Over a year ago

my fault. I'm sure he can figure it out. hopefully, he'll invest some time and learn regex.

user6363065 Over a year ago

@KMC thanks for your help. that's work great for me, in my coding i need to add some more patterns like "15-xxxxx-0x","800-xxxxx-0x" etc. so I am trying to understand who write var pattern. I am using msdn.microsoft.com/en-us/library/ff650303.aspx . Any advice where i get clear idea of Regex Pattern. I dont have much time to go in details right now.

dfdsfdsfsdf Over a year ago

You can learn regex expressions from here. Give it a try and if you're really stuck then reply and I'll give you some help. msdn.microsoft.com/en-us/library/az24scfc(v=vs.110).aspx

user6363065 Over a year ago

@KMC...I got it. Thank you so much for your help.

Bob Kaufman · Accepted Answer · 2016-05-20 21:58:29Z

The C# Substring method is not

String.Substring( int startIndex, int endIndex )

as your code suggests, rather it is

String.Substring( int startIndex [, int numberofCharacters ] )

Given that, if you're looking for two characters, you'd use:

string lastPart = partnoveri.Substring(partnoveri.IndexOf("-0"), 2);

That being said, I'd opt for @KMC's regular expression solution. While Substring will work in the case of your example, it will fail if the fourth character is zero, as in 10-0283-01

Luuk · Accepted Answer · 2021-02-13 18:57:04Z

Just reading about Ranges introduces in C# 8.0 spec.

Reading this question:

I have string "10-1283-01" the length going to be same , i want to check is that string like "10-xxxx-0x" only want first 3 character like "10-" and last but one two character like "-0"."

one can do (since c# 8.0 specs):

string partno = "10-1283-01"; Console.WriteLine($"{partno[0..3]}"); // returns "10-" Console.WriteLine($"{partno[^3..^1]}"); // returns "-0"

mjpolak · Accepted Answer · 2016-05-20 21:54:46Z

To receive two last characters you can use substring like below:

partnoveri.Substring(partnoveri.Length-2, 2);

You can also use Regular Expression for this case.

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