Custom Numeric Format Strings: Dynamic Decimal Point

Question

I am trying to format a double in C# such that it uses the thousand separator, and adds digits upto 4 decimal places.

This is straight forward except that I dont want to have the decimal point if it is an integer. Is there a way to do this using the custom numeric format strings rather than an if statement of tenary operator?

Currently I have:

string output = dbl.ToString(dbl == (int)dbl ? "#,##0" : "#,##0.####");

Thanks

Answer 1

No, there is not any built-in format string for this. Your current solution is the best way to accomplish this.

MSDN lists both the standard numeric format strings and custom numeric format strings, so you should be able to see for yourself that none directly matches your needs.

Answer 2

I believe your second format string of "#,##0.##" should be exactly what you want -- the # format character is a placeholder that will NOT display zeros.

If you had "#,###.00" then you would get trailing zeros.

test code:

double d = 45.00;
Console.Writeline(d.ToString("#,##0.##"));

Gives output of "45". Setting d to 45.45 gives output "45.45", which sounds like what you're after.

So you had the answer after all! ;)

Incidentally, there's a handy cheat-sheet for format strings (amongst other handy cheat-sheets) at http://john-sheehan.com/blog/net-cheat-sheets/