how to increase the value of an integer in a string

Question

Ok I currently have this code

        public int i = 0; //this is outside of the private void button1_click
        string str = txtEmail.Text;
        int pos = str.LastIndexOf("@");
        string str2 = str.Substring(pos);
        string str3 = str.Substring(0, str.LastIndexOf("@"));
        txtEmail.Text = str3 + i++ + str2;

it splits the email into 2 string then combines them with an integer between them, But I want it to change the integer. But that code just makes it lets saying the text becomes awesome1@email.com when i press the button to increase the 1 to a 2 it just does this instead. awesome12@email.com and so on. how do i get it to just add 1 to the 1 and not put a 2 next to the 1?

I think you need to show us the loop (I suspect) you're using, if Jon's answer is not what you're looking for. — Alex In Paris, Mar 26 '12 at 09:24
variable i = 0 currently and is located outside of the button_click event it is a public integer and @AlexInParis im not using a loop — Ian Lundberg, Mar 26 '12 at 09:28
You need to keep track of the original string, or at least the last index of the number you inserted in order to accurately replace your int value. — tobias86, Mar 26 '12 at 10:50

Brad Rem · Accepted Answer · 2012-08-04T23:09:27.250

1

I tested the following and it looks like it solves your problem. Change this line of yours:

string str = txtEmail.Text;

To this:

string str = txtEmail.Text.Replace(string.Format("{0}@", i - 1), "@");

It sets it up so that your email addresses will be in the form of:

awesome1@email.com 
awesome2@email.com 
awesome3@email.com 
etc.

edited Aug 04 '12 at 23:09

answered Mar 26 '12 at 17:48

Brad Rem

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score 0 · Answer 2 · answered Mar 26 '12 at 09:17

0

Not sure where i is coming from in this code but hopefully this will work

    string str = txtEmail.Text;
    int pos = str.LastIndexOf("@");
    string str2 = str.Substring(pos);
    string str3 = str.Substring(0, str.LastIndexOf("@"));
    txtEmail.Text = str3 + (i++).ToSting() + str2;

answered Mar 26 '12 at 09:17

Jon

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doesnt work still just adds on to the string and makes it longer doesnt replace the number with the +1 version of itself – Ian Lundberg Mar 26 '12 at 09:25
Agreed although I dont think in this case it will be too much of a memory problem – Jon Mar 26 '12 at 09:31
Better to use string.Concat, avoid the GC overhead of making a stringbuilder – Cronan Mar 26 '12 at 09:38
Also, this might answer it: http://stackoverflow.com/questions/21078/whats-the-best-string-concatenation-method-using-c – Cronan Mar 26 '12 at 09:38
@RickHoving i dont think string builder works that way? cause doing that gave me an error saying that stringbuilder "doesnt have a constructor that contains 3 arguments". – Ian Lundberg Mar 26 '12 at 09:39
@IanLundberg yeah I cinda messed up there, look at my answer for the correct usage. – Rick Hoving Mar 26 '12 at 09:42

Tim Schmelter · Answer 3 · 2012-03-26T09:45:04.740

This should work:

String email = "awesome1@email.com";
String[] tokens = email.Split(new char[] { '@' }, StringSplitOptions.RemoveEmptyEntries);
const String allowed = "0123456789";
String part1 = "";
String numberStr = "";
foreach (char c in tokens[0].Reverse())
{
    if (allowed.Contains(c) && part1.Length==0)
    {
        numberStr += c;
    }
    else
    {
        part1 += c;
    }
}
part1 = new String(part1.Reverse().ToArray());
int number = int.Parse(new String(numberStr.Reverse().ToArray()));
String result = String.Format("{0}{1}@{2}", part1, number++, tokens[1]);

Although it looks a little bit cumbersome. Accept a Regex answer if there's one.

Antonio Bakula · Answer 4 · 2012-03-26T10:11:06.050

This will work

public static string IncNumberBeforeAt(string text)
{
  int lastAt = text.LastIndexOf('@');
  if (lastAt != -1)
  {
    int pos = lastAt - 1;
    string num = "";
    while (text[pos] >= '0' && text[pos] <= '9')
    {
      num = text[pos] + num;
      pos--;
      if (pos < 0)
        break;          
    }
    int numInc = int.Parse(num) + 1;
    return text.Replace(num.ToString() + "@", numInc.ToString() + "@");
  }
  else
  {
    return text;
  }
}

test

IncNumberBeforeAt("awesome1@email.com"); // => returns awesome2@email.com
IncNumberBeforeAt("awesome234@email.com"); // => returns awesome235@email.com
IncNumberBeforeAt("email.com"); // => returns email.com
IncNumberBeforeAt("5@email.com"); // => returns 6@email.com

Test `"awesome๐1@email.com"`. `char.IsNumber` (and even `char.IsDigit`) allows to many chars. — Tim Schmelter, Mar 26 '12 at 10:02

score 0 · Answer 5 · answered Mar 26 '12 at 10:52

0

You will have to keep track of your original e-mail address:

e.g.

string originalEmail = "test@gmail.com";

var parts = originalEmail.Split('@');

txtEmail.Text = string.Format("{0}{1}@{2}", parts[0], i++, parts[1]);

answered Mar 26 '12 at 10:52

tobias86

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that still does the same thing aka it doesnt work :/ thanks for trying though – Ian Lundberg Mar 26 '12 at 10:55
This will only work if you keep using your original email address, i.e. the one without the integer. – tobias86 Mar 26 '12 at 11:21

how to increase the value of an integer in a string

5 Answers5