问题
I need all values to rounded to two decimal places. So 1.401 should round to 1.40, but Math.Round(value, 2) rounds to 1.4.
How can I force the trailing zero?
回答1:
1.4 is the same as 1.40 - you just want to display it differently. Use a format string when calling ToString - like value.ToString("0.00")
回答2:
1.4 == 1.40 the only time you'd ever need a trailing 0 is when you display the number..i.e. format it to string.
.ToString("N2");
回答3:
I know this is an old question, but might help someone!
I am using a c# xml class to populate and then serialise to xml. One of the values is a double. If I assign a '7' to the value this gets serialised to '7' when I actually need '7.00'. Easiest way round this was just to do:
foo = doubleValue + 0.00M
And that makes the value 7.00 instead of just 7. Thought this was better then doing a ToString and then parsing it back.
回答4:
The trailing zero is more of a formatting than a value issue, so use
foo.ToString("0.00")
回答5:
The trailing zero is just a presentation. Math-wise, 1.40 and 1.4 are equivalent.
Use formatting instead to present it with the 2 decimal places:
String.Format("{0:0.00}", 1.4);
or
yourNumber.ToString("0.00");
回答6:
It is a number (double?), so it doesn't have a trailing zero - you have to make it text and force a trailing zero.
回答7:
It has to do with whether you use a decimal or a double.
While internally (as it appears from the Source Code) Math.Round() preserves the trailing zeros even on a double, still the fact that it is saved as a double in memory causes automatically to remove all trailing zeros
So if you do want tailing zeros, you can either use the string display functions to format it as others have answered, or make sure to pass in the original value as a decimal (causing to use internally Decimal.Math.Round which will deal only with decimals), and make sure to not cast the result to a double and also not to save it in a double variable.
Similarly if you have a decimal and you don't want trailing zeros, just cast it to a double (you can either cast the input to Math.Round or the result, it doesn't matter as long as somewhere in the way it is becoming a double).
来源：https://stackoverflow.com/questions/12307630/math-round-not-keeping-the-trailing-zero