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

Henrik M Madsen · Accepted Answer · 2024-02-19 13:42:35Z

8

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! ;)

edited Feb 19, 2024 at 13:42

Henrik M Madsen

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answered Sep 10, 2009 at 13:27

Dr Herbie

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Comments

Noldorin · Accepted Answer · 2009-09-10 11:21:47Z

7

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.

answered Sep 10, 2009 at 11:21

Noldorin

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7 Comments

Noldorin Over a year ago

No problem. And yeah, if you want to make the method more convenient, I suggest you just wrap it into an extension method.

LukeH Over a year ago

This is incorrect. The OP's second format string, #,##0.####, does exactly what they require.

Noldorin Over a year ago

@Luke: Take a closer look before commenting. That format string will format 2.34 and 2.34 for example, which is not whast the OP wants.

LukeH Over a year ago

@Noldorin: I'm not sure what you meant in your comment. Can you elaborate? As far as I can tell that format string matches the requirements in the question.

Noldorin Over a year ago

@Luke: As I see it, if the number is integral, he wants to display no decimal points, whereas is the number is non-integral, he wants to display exactly 4 decimal points (no more, no less).

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