Topic: Increment a Number in a String

[SteveK]

how about:

Code: [Select]

Console.WriteLine(Incr("asdf0004", -5));~'J'~

At the moment I'm not sure what is better for my purposes, to go into the negatives or to floor at 0, but since I said "stop at 0" near the start of the thread I've stayed with that. In time it might change.

[Glenn R]

A quickie with regular expressions:

Code: [Select]


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Text.RegularExpressions;

namespace IncStr
{
    class Program
    {
        static void Main(string[] args)
        {
            //string test1 = "ab12cd-34e";
            string test2 = "a1.9b";
            //string test3 = "ab12cd34e66";

            string pattern = "[-+]?[0-9]+";

            MatchCollection matches = Regex.Matches(test2, pattern);

            if (matches == null || matches.Count == 0) return;

            foreach (Match match in matches)
            {
                Console.WriteLine("{0}Match index: {1}", Environment.NewLine, match.Index);
                Console.WriteLine("{0}Match value: {1}", Environment.NewLine, match.Value);
                Console.WriteLine("{0}Match length: {1}", Environment.NewLine, match.Length);
            }

            // work with the last match only...
            Match lastMatch = matches[matches.Count - 1];

            int testIncrement = 2;

            int newValue;
            bool result = int.TryParse(lastMatch.Value, out newValue);

            string replacedString = test2.Substring(0, lastMatch.Index) +
                                    (newValue + testIncrement) +
                                    test2.Substring(lastMatch.Index + lastMatch.Length);

            Console.WriteLine(replacedString);

            Console.ReadLine();
        }
    }
}


[SteveK]

Thanks Glenn. 
It doesn't keep zero prefixes, but I'm happy to see a regex example anyway.

[Glenn R]

It's just an example to show what's possible. It's up to you or somebody else to come up with the arcane regex incantation needed

[SteveK]

the arcane regex incantation needed

That's exactly what I thought when I was trying to work it out - by the time I learn the required regex combination I could have twice written something from scratch that does it. Probably worthwhile to know, but it's a language inside a language.

[Kerry]

noticed this a couple of weeks ago
Regex Editor Add-on
http://visualstudiogallery.msdn.microsoft.com/en-us/55c24bf1-2636-4f94-831d-28db8505ce00?SRC=VSIDE

Haven't made time to look at it yet.