how to place - in a string

I have a string "8329874566". I want to place - in the string like this "832-98-4566"

Which string functio开发者_开发问答n can I use?

---

I would have done something like this..

  string value = "8329874566";
  value = value.Insert(6, "-").Insert(3, "-");

---

You convert it to a number and then format the string. What I like most about this is it's easier to read/understand what's going on then using a few substring methods.

string str = "832984566";
string val = long.Parse(str).ToString("###-##-####");

---

There may be a tricky-almost-unreadable regex solution, but this one is pretty readable, and easy.

The first parameter of the .Substring() method is where you start getting the characters, and the second is the number of characters you want to get, and not giving it sets a default as value.length -1 (get chars until the end of the string):

String value = "8329874566";

String Result = value.Substring(0,3) + "-" + value.Substring(3,2) + "-" + value.Substring(6);

--[edit]--

Just noticed you didn't use one of the numbers AT ALL (number '7') in the expected result example you gave, but if you want it, just change the last substring as "5", and if you want the '7' but don't want 5 numbers in the last set, let it like "5,4".

---

Are you trying to do this like American Social Security numbers? I.e., with a hyphen after the third and and fifth numerals? If so:

string s = "8329874566";
string t = String.Format("{0}-{1}-{2}", s.Substring(0, 3), s.Substring(3, 2), s.Substring(5));

---

Just out of completeness, a regular expression variant:

Regex.Replace(s, @"(\d{3})(\d{2})(\d{4})", "$1-$2-$3");

I consider the Insert variant to be the cleanest, though.

---

This works fine, and I think that is more clear:

    String value = "8329874566";
    value = value.Insert(3, "-").Insert(6, "-");

The console outputs shows this: 832-98-74566

---

If the hyphens are to go in the same place each time, then you could simply concatenate together the pieces of the orginal string like this:

//               0123456789 <- index
string number = "8329874566";
string new = number.Substring(0, 3) + "-" + number.Substring(3, 2) + "-" + number.Substring(5);

For a general way of making mutable strings, use the StringBuilder class. This allows deletions and insertions to be made before calling ToString to produce the final string.

---

You could try the following:

string strNumber = "8329874566"
string strNewNumber = strNumber.Substring(0,3) + "-" + strNumber.Substring(4,2) + "-" strNumber.Substring(6)

or something in this manner

---

string val = "832984566";  
string result = String.Format("{0}-{1}-{2}", val.Substring(0,3), val.Substring(3,2), val.Substring(5,4));

---

var result = string.Concat(value.Substring(0,3), "-", value.Substring(3,2), "-", value.Substring(5,4));

or

var value = "8329874566".Insert(3, "-").Insert(6, "-");

---

Now how about this for a general solution?

// uglified code to fit within horizontal limits
public static string InsertAtIndices
(this string original, string insertion, params int[] insertionPoints) {

    var mutable = new StringBuilder(original);

    var validInsertionPoints = insertionPoints
        .Distinct()
        .Where(i => i >= 0 && i < original.Length)
        .OrderByDescending(i => i);

    foreach (int insertionPoint in validInsertionPoints)
        mutable.Insert(insertionPoint, insertion);

    return mutable.ToString();
}

Usage:

string ssn = "832984566".InsertAtIndices("-", 3, 5);

string crazy = "42387542342309856340924803"
    .InsertAtIndices(":", 1, 2, 3, 4, 5, 6, 17, 200, -1, -1, 2, 3, 3, 4);

Console.WriteLine(ssn);
Console.WriteLine(crazy);

Output:

832-98-4566
4:2:3:8:7:5:42342309856:340924803

Overkill? Yeah, maybe...

_{P.S. Yes, I am regex illiterate--something I hope to rectify someday.}

---

A straightforward (but not flexible) approach would be looping over the characters of the string while keeping a counter running. You can then construct a new string character by character. You can add the '-' character after the 3rd and 5th character.

A better approach may be to use a function to insert a single character in the middle of the string at a specific index. String.Insert() would do well. The only thing to pay attention to here is that the string indexes will get off by one with each insert.

EDIT more language-specific as per comments