Best way to parse a string to a float with both "," and "." as fraction separator? (For a number < 5)

Question

This is kind of related to my previous question, but not really. I have an input of which I don't know the culture. So it can both use ',' and '.' as separator for the fraction. The number will never be >5 though, so we can be rather sure if there's a separator, it will be for the fraction.

I was looking at the TryParse method. It accepts a NumberStyles argument. But I don't see anything about fraction separator or the like..

Am I missing something again or is there a better way to reach my goal?

Thx for keeping the post updated after the discussion in the comments. — Boris Callens, Mar 26 '09 at 08:43

Mehrdad Afshari · Accepted Answer · 2008-12-23T17:13:03.730

9

Try this:

float.TryParse(myString.Replace(',', '.'), out myfloat);

EDIT: as Jon mentioned, the following way is recommended:

float.TryParse(myString.Replace(',', '.'), 
               System.Globalization.NumberStyles.Float, 
               System.Globalization.NumberFormatInfo.InvariantInfo, 
               out myFloat);

edited Dec 23 '08 at 17:13

answered Dec 23 '08 at 12:48

Mehrdad Afshari

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If you explicitly want to use "." as the separator, I'd pass in CultureInfo.InvariantCulture as well. – Jon Skeet Dec 23 '08 at 12:51
This can fail if there are also thousant separators. – Toon Krijthe Dec 23 '08 at 12:52
@Gamecat: The question says the number is less than 5. – Mehrdad Afshari Dec 23 '08 at 12:54
Gamecat - that's exactly what I was just thinking! I guess you'd have to get to the end of the string and work backwards, treating the first , or . as the decimal separator and ignoring everything you subsequently found. – robsoft Dec 23 '08 at 12:54
@Mehrdad - oops. I skimmed that, too. :-) – robsoft Dec 23 '08 at 12:54
@Gamecat: Sure, but a number with a thousand separators is way too large (or rather, too small) to fit into a float anyhow. – Dana Dec 23 '08 at 12:56
@Dana, I think you are underestimating float type. – Mehrdad Afshari Dec 23 '08 at 12:58
@Mehrdad - I might be :P Can it actually store a fraction that small? With a thousand separators in it? – Dana Dec 23 '08 at 13:01
"1,234.5" is a valid float and it has a thousand separator. – Mehrdad Afshari Dec 23 '08 at 13:03
@Mehrdad - Haha, I misread GC! I read him as saying if there were a thousand commas it would fail :P As in 0.000,000,..[998 more commas]..,001 – Dana Dec 23 '08 at 13:07
@Mehrdat Afshari, I know, but I just added the remark for if somebody else uses the solution without the constraint. – Toon Krijthe Dec 23 '08 at 13:10
Mehrdad or someone else with enough points please edit the text to include Jon's hint with CultureInfo.InvariantCulture. Thanks. – Christoph Rüegg Dec 23 '08 at 13:34

Best way to parse a string to a float with both "," and "." as fraction separator? (For a number < 5)

1 Answers1