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.netvb.netformattingtostringnumeric
ElektroStudios
ElektroStudios

Reputation: 20494

Custom numeric decimal format

Problem:

I would like to format a Double number with undetermined decimal precisión (eg. value.ToString("n2") ) but eliminating/discarding the decimals in case of all the decimals are 0, or in other words, return an integer string instead of a decimal string in case of all its decimals are zeroes.

Question:

How I could solve the decimal formatting problem explained above?. (please, see the Remarks)

Expected Results:

This code will produce the string 1,00, but it should produce the string 1:

Dim value As Double = 1.0R
Dim format As String = value.ToString("n2", CultureInfo.CurrentCulture.NumberFormat)
Debug.WriteLine(format)

This code will produce the string 1,01, doesn't need changes because it has a non-zero decimal:

Dim value As Double = 1.01R
Dim format As String = value.ToString("n2", CultureInfo.CurrentCulture.NumberFormat)
Debug.WriteLine(format)

Just another example of the expected formatting with a decimal precision of 2:

1
1,01
...
1,09
1,10 - Note the last zero is not eaten.
1,11
...
2

Research:

I've been reading these docs on MSDN but I didn't seen how to solve that.

Double.ToString Method (String)

Standard Numeric Format Strings

Custom Numeric Format Strings

NumberFormatInfo.NumberDecimalDigits Property .

Remarks:

· I'm looking for the proper and efficient way to do this, I'm aware of doing a Substring or things like that on the resulting string to search or count the resulting zeroes.

· I would like to keep using my current culture's NumberFormat, if that matters.

· I will clarify that in my real scenario I'm using random numbers then I can't know whether the value to format will have zero decimals (1,00) or non-zero decimals (1,99) and/or its decimal precision/length.

Upvotes: 1

Views: 654

Answers (2)

sloth
sloth

Reputation: 101152

You can use something like "0.##" as your format string:

Dim values = {1.0000R, 1.0R, 1.1R, 1.100R}
For Each value in values
    Debug.WriteLine(value.ToString("0.##", CultureInfo.CurrentCulture.NumberFormat))
Next

Output will be 1, 1, 1.1 and 1.1, which seems to be what you want (the loss of precision may or may not be what you want).

This is a custom numeric format with digit placeholders, as shown here: Custom Numeric Format Strings.

An alternative are the Standard Numeric Format Strings; especially the general format specifier, which you can use without a precision specifier (which may or may not be what you want).

In response to your edit/comment:

There's no simple single format string you can use, but you could use a simple workaround like this: 

value.ToString(If(Math.Abs(value mod 1) < Double.Epsilon, "0", "0.00"), CultureInfo.CurrentCulture.NumberFormat)

Upvotes: 1

admax
admax

Reputation: 1671

value.ToString("G2")

this should work

Upvotes: 1

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