Converting [string].ToString([custom format])

Question

How can I achieve formatting string to custom format:

int value = 5000;
String.Format("{0:## ###}", value);
value.ToString("##");

but with value as string, without using conversion to number? something like this:

String.Format("{0:## ###}, "5000");

** UPDATE:

I'm trying to create a generic function:

    public string FormatString(string value, string format = "") {
        if (value == null){
            return "";
        }

        return String.Format("{0:" + format + "}", value);
    }

    public bool OtherFunction(id){
          var data = dc.GetData(id);
          ViewBag.DescriptionText = FormatString(data.Description).Replace("\n", "<br />");
          ViewBag.Phone = FormatString(data.Phone, "(##) ####-#####");
          ViewBag.City= FormatString(data.City);
          [...]
    }

It's really unclear what you're trying to achieve, I'm afraid. The "## ###" format is specifically for formatting numbers. What would you expect it to do when given "hello world"? — Jon Skeet
– Jon Skeet, Commented Dec 9, 2013 at 15:22
You can't, if you need to format a string, you have to write a formatter for said string, which is probably far more complex than simply converting the string into a number. — Tobberoth
– Tobberoth, Commented Dec 9, 2013 at 15:24
With "Hello World", I will call the function without specifying format.. So It would be just "Hello World".. — Andre Figueiredo
– Andre Figueiredo, Commented Dec 9, 2013 at 15:26
So, there is not a way without do a "isNumber(value) then convert"? — Andre Figueiredo
– Andre Figueiredo, Commented Dec 9, 2013 at 15:27
@IanNelson... thinking twice, It's not making sense.. I wanted to format a string number that I have in some variables from DB, but putting the verification for null string and the formatting in a function and just calling the function for every case.. but it all would be avoided if the "string number" would be really a numeric type, which sadly I can't change in the moment.. — Andre Figueiredo
– Andre Figueiredo, Commented Dec 9, 2013 at 15:36

Carnifex · Accepted Answer · 2013-12-09 19:03:42Z

1

I don't think something like this exists. Like Jon said, this was design for numbers.

If you want just "format" with # you could write simple function, something like this

public string FormatString(string value, string format = "")
{
    if (String.IsNullOrEmpty(value) || String.IsNullOrEmpty(format))
        return value;

    var newValue = new StringBuilder(format);

    for (int i = 0; i < newValue.Length; i++)
    {
        if (newValue[i] == '#')
            if (value.Length > 0)
            {
                newValue[i] = value[0];
                value = value.Substring(1);
            }
            else
            {
                newValue[i] = '0';
            }
    }

    return newValue.ToString();
}

Of course this is very simple one. You will have to check and decide what to do if format is too long (like here: fill with '0') and when he format is too short (here: just 'truncate' rest of value).

But I think you have an idea how to do this.

Somewhere on my disk I have code for something like this: formatting number in special ways/pattern for invoice number. If I will find this, I'll make some post on blog and paste the link

answered Dec 9, 2013 at 19:03

Carnifex

5413 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Andre Figueiredo Over a year ago

Excellent! Since direct string format is not possible, something like that is what I was trying to achieve.

Thomas Weller · Accepted Answer · 2013-12-09 15:25:21Z

0

"5000" is a string. The only overload available for string.ToString() is the one with an IFormatProvider [1]. While you could actually implement that, you'll probably end up in something similar to int.Parse() which you don't like.

[1] http://msdn.microsoft.com/de-de/library/29dxe1x2(v=vs.110).aspx

answered Dec 9, 2013 at 15:25

Thomas Weller

61.2k23 gold badges143 silver badges263 bronze badges

Collectives™ on Stack Overflow

Converting [string].ToString([custom format])

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related