Convert a string to double

Question

I need help converting a string to double with 7 decimals. I have a string "00000827700000" and need it converted to 82.77

Tried using String.Format() with {0:N7} without success.

Is the format always like that? With the stars, and the exact number of characters? Are you sure that double is the most appropriate type here, rather than decimal? — Jon Skeet
– Jon Skeet, Commented Jun 19, 2012 at 20:23
I've edited my answer based on the edited question. It would really help if you'd clarified this to start with - and answered the other questions posed in comments. — Jon Skeet
– Jon Skeet, Commented Jun 19, 2012 at 20:30
Welcome to StackOverflow! By the way, having Jon Skeet answer your first question is like having Eric Clapton walk up to you to help when you asked for someone to "teach you a couple chords". Please heed his advice. — Zoot
– Zoot, Commented Jun 19, 2012 at 20:46

Jon Skeet · Accepted Answer · 2012-06-19 20:36:23Z

7

It looks like you could use:

decimal x = decimal.Parse(text.Substring(0, 7) + "." +
                          text.Substring(7),
                          CultureInfo.InvariantCulture);

That would actually parse it to 82.7700000, as decimal preserves trailing zeroes (to an extent) but maybe that's good enough? It not, you could change the second argument to

text.Substring(7).TrimEnd('0')

Note that I'd strongly recommend you to at least consider using decimal instead of double. You haven't explained what this value represents, but if it's stored as decimal figures which you need to preserve, it smells more like a decimal to me.

edited Jun 19, 2012 at 20:36

answered Jun 19, 2012 at 20:25

Jon Skeet

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3 Comments

CaffGeek Over a year ago

well, now I can't write it any clearer than you have done. I would still use TryParse, but other than that it wouldn't be any different. Actually, the second argument could just be text.Substring(7).TrimEnd('0') now since there is no garbage characters.

Jon Skeet Over a year ago

@Chad: I'd only use TryParse if it were legitimate for this to be bad data. I expect it's actually machine-generated, and I'd be happy with an exception being thrown here just as I would if (say) XML parsing failed. Good point on the Substring call though - editing...

CaffGeek Over a year ago

fair enough, I actually thought of a potentially simpler way, see my edited response. Not sure which is quicker.

CaffGeek · Accepted Answer · 2012-06-19 20:45:18Z

3

Based on the edit, it could be simplified as

var text = "00000827700000";
var x = decimal.Parse(text, CultureInfo.InvariantCulture) / 10000000;
Console.Write(String.Format("{0:N7}", x));

edited Jun 19, 2012 at 20:45

answered Jun 19, 2012 at 20:29

CaffGeek

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2 Comments

CaffGeek Over a year ago

This is the best I can come up with, formats with 7 decimals showing, and converts the value to a proper decimal, rather than leaving it stringly typed

Jon Skeet Over a year ago

Yes, that's a good point - I had originally considered dividing, but it was a pain when the two pieces were separated. Now it's a very natural answer.

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