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c#stringformatting
Richard J Foster
Richard J Foster

Reputation: 4388

When using String.Format is there a simple way to add parenthesis around a string value if it is not null or empty

I am attempting to isolate (for localization purposes) the formatting of some messages. In one of the cases, I have several parameters, some of which may be an empty string. An example is probably called for here....

If the parameters are Parameter one and Parameter two then I want the result to be Some message Parameter one (Parameter two).

If the parameters are Parameter one and string.Empty then I want the result to be Some message Parameter one

If Parameter two was a numeric value, then I could use something like:

String.Format("Test {0}{1:' ('#')'}", "Parameter one", 12);

This operates as I'd expect - specifically if the second parameter is null the output is just Test Parameter one.

Unfortunately I haven't (yet) found a similar option which works with string parameters. Is there one?

Clarification: I am fully aware of numerous ways to get the result I need in code. I specifically want to know if there is a similar built-in mechanism for strings to the numeric one shown above.

Upvotes: 7

Views: 4885

Answers (6)

Grzenio
Grzenio

Reputation: 36649

You could write your own wrapper of String.Format (untested):

string MyFormat(string format, params object[] args)
{
  object[] newArgs = new object[args.Length];
  for(int i=0; i<args.Length; i++)
  {
    if(args[i] is string)
    {
      newArgs[i] = String.IsNullOrEmpty(args[i] as string) ? "" : string.Format("({0})", args[i]);
    }
    //numeric cases etc
    else
    { 
      newArgs[i]=args[i];
    }
  }
  return string.Format(format, newArgs);
}

Upvotes: 0

Andy_Vulhop
Andy_Vulhop

Reputation: 4789

You could create an extension method to help handle this and make it a little more concise.

public static string SomeWellNamedExtension(this string s)
{
    if(string.IsNullOrEmpty(s))
        return "";

    return string.Format("({0})", s);
}

This method will handle the null/empty check and the parens. It's a pretty specialized method, so it's not likely to be useful almost anywhere else. But then your code would be like:

string.Format("Test {0}{1}, paramOne, paramTwo.SomeWellNamedExtension());

However, ymmv. This will affect your format string in that the parens are no longer its responsibility. I can't think of many super elegant ways of handling the use case you are talking detailing.

Upvotes: 2

Mau
Mau

Reputation: 14468

var s = System.String.IsNullOrEmpty(param2) ? string.Format(...) : string.Format(...)

Upvotes: 0

Neil Barnwell
Neil Barnwell

Reputation: 42125

Unless you define a function that encloses a value in brackets, I can't see how you do it inline?

A simple example:

string.Format("Some message {0} {1}", "Parameter one", EncloseInParenthsisIfNotEmpty(""))

public string EncloseInParenthsisIfNotEmpty(string input)
{
    if (string.IsNullOrEmpty(input)) return "";
    return string.Format("({0})", input);
}

Upvotes: 1

Andy_Vulhop
Andy_Vulhop

Reputation: 4789

Depends on your situation, but you could do 

string.Format(yourFormatString, paramOne, paramTwo).Replace("()", "");

No guarantees, as it is not fool-proof and makes the large assumption that your resulting string would only have "()" if paramTwo was empty.

Upvotes: 2

Chris Marisic
Chris Marisic

Reputation: 33098

You could always attempt writing your own custom string formatter by implementing IFormatProvider and ICustomFormatter

Then invoke it as 

var stringValue = string.Format(new NewCustomStringFormatInfo(),
     "Test {0}{1:' ('#')'}", "Parameter one", 12)

Upvotes: 4

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