In my application, I have a TextBlock that I display a Double number in after the user presses a button. This number can be a very small decimal or a very large number needing exponential notation (i.e. 3.43e12). The problem is, the program prints so many digits that it overflows my TextBlock and the user can't see all the valid information.
So how can I restrict the Double to print so to not overflow the TextBlock?
The code I am using to set the text is:
theTextBox.Text = (split * input).ToString();
EDIT: Someone asked for specific examples, so I thought I would clarify something. I basically want the string to never be longer than, say, 10 characters. That way it will fit in the TextBlock. I guess the trick is, when should those 10 characters be decimal places, whole numbers, or scientific notation that is the trick...
Use Double.ToString(String), giving an appropriate format specifier, as described at http://msdn.microsoft.com/en-us/library/kfsatb94.aspx.
Have a looksee here
http://msdn.microsoft.com/en-us/library/0c899ak8.aspx
You can put your format string in as a param to the ToString method
Related
I'm looking to accept digits and the decimal point for forms, using WPF application.
I am new to WPF
I want a textbox that takes only numeric values, in the format
12.3456
that is, 2 places before decimal point and 4 places after it.
Too bad TextBox has no Property to set the DataType of the field and the amount of Decimal Places it can hold, had to make a UserControl that does exactly what you want.
Offtopic aside, use Regex, I usually use this website to build them.
For a text display in Unity3D. Wht would I do if I wanted to remove all but say 2 decimals from a float? To clarify what I want to do, please see the example below:
Say I have the floats:
1.25013
1.9012
1.029
Now, in Unity what should I do if I want to shorten them so only two decimals remain i.e returning 1.25, 1.90 and 1.02 before displaying the string such as on a UI.Text ?
I have looked into string formatting and stuff like Math.Floor without success.
As said in the comments, if it is just for display the correct way to solve this problem is pass in a numeric format to a .ToString call.
To get the format you described you would want the format string f2, that would create a fixed-point number with two decimal points that will look like 1234.50
UI.Text = someNumber.ToString("f2");
If you would like a , in the number when you have more than 3 digits to the left of the decimal place like 1,234.50 use n2 instead of f2
UI.Text = someNumber.ToString("n2");
I am getting data into a text field and I need to display it as a percentage. Is there a function to perform this?
Ex: in my column I have "0.5", "0.1","0.2","0.25" etc., which needs to be displayed as
50%,10%,20%,25% etc., What is the best way to do it?
You should do this in two phases:
Parse the text as a number so you've got the value as your "real" type. (As a general rule, parse from text as early as you can, and format to a string as late as you can... operations between the two will be a lot simpler using the natural type.)
Format the number as a percentage using the standard numeric format string for percentage
So:
decimal percentage = decimal.Parse(input);
string output = percentage.ToString("p0");
Notes:
You should consider both input and output culture; are you always expecting to use "." as the decimal separator, for example?
Use decimal rather than double to exactly represent the value in the text (for example, the text could have "0.1" but double can't hold a value of exactly 0.1)
You can add things like desired precision to the formatting; see the linked docs for details; the example gives just an integer percentage, for example
Easiest would be to parse it (must be a double) then convert it back to a string, formatting it as a percentage.
var percentageString = double.Parse(doubleString).ToString("p1");
Now, some of you hoity-toity types may say that decimal is the correct type to use in this case.
Well, yes, if you need an additional 12-13 digits of precision.
However, most of us real folk (and I'm all about keeping it real) are fine with double's 15-16 digits of precision.
The real choice is whether or not your code is using doubles or decimals in the first place. If you are using doubles in your code, just stick with doubles. If decimals, stick to decimals. What you definitely do want to avoid is having to convert between the two any more than is absolutely necessary, as there be dragons. And unexpected runtime bugs that can corrupt your data. But mostly dragons.
I wish to extract double value completely when I am debugging an application, so that I can use it to construct a test case to feed into my geometry algorithm.
How to extract the double value out-- down to very last decimal places allowed by the double datatypes in C#-- and output it in either debugger windows, or using Console.WriteLine command?
Edit: My problem is that the algorithm that takes the double value as input will only fail if I insist of input the whole double value, right down to the very last digit. And since I want to reproduce it in a test case, that's why I would need such a full representation of the double value.
I have a DoubleConverter class which does exactly what you want, by the sounds of it. Use it like this:
string text = DoubleConverter.ToExactString(doubleValue);
You need to make sure you understand that just because the output has a large number of digits, that doesn't mean it has that much precision. You may want to read my article on binary floating point in .NET for more information - or you may be aware of all of this to start with, of course.
Note that if you only want a string value which can be round-tripped, you don't need any extra code - just use the "r" format specifier:
string text = doubleValue.ToString("r");
I agree with Jackson Pope's general approach of using tolerance in equality comparisons for tests, but I do find it useful sometimes to see the exact value represented by a double. It can make it easier to understand why a particular calculation has come out one way or another.
Instead of trying to output a binary number as a decimal number to a very large number of decimal places and do an exact comparison, instead do a comparison with an epsilon value that is your acceptable error and set epsilon to be very small. E.g.
double epsilon = Math.Abs(actual - expected);
Assert.That(epsilon, Is.LessThan(0.000000000001);
When using double.Parse, it seems to like to string away any trailing (insignificant) zeros from the string that I'm converting. I would like double.Parse to keep to places after the decimal. For example, here is some code:
tobereturned.MouseSensitivty = double.Parse(String.Format("{0:#.##}", tempstring[1]));
Debug.WriteLine("Converted " + String.Format("{0:#.##}", tempstring[1]) + " to " + tobereturned.MouseSensitivty);
The Debugger then writes
Converted 4.00 to 4
So it seems like double.Parse is doing something fishy here.
P.S. MouseSensitivity is also of the type double, so I can't do any string operations on it.
Your question is meaningless. Doubles don't have "places after the decimal" in the first place. They don't store anything that looks remotely like a "decimal representation of a number" internally. In fact, they don't store anything internally that even looks like recognizable text.
It reports 4 because 4.00 is exactly equal to 4. It is displaying the number "exactly four with no fractional part" as text according to its default rules for converting numbers to text.
Please read this. Yes, it is long, and difficult, but it is simply not possible to use floating-point numeric types properly without a real understanding of this material - and it doesn't matter what language you're using, either.
The double data type is simply a number; it doesn't keep track of the string that was parsed to create the value. Its string representation only comes into play when .ToString() is called.
If you know you always want two places after the decimal you can right-fill with zeros.
it is not the job of the double type to keep track of your desired display format.
Double does not store redundant zeros. In your view or presentation layer, you might want to format it to show you want it to appear, e.g., String.Format("{0:#.##}", doubleVariable)