The following examples show how to format float numbers to string in C#. You
can use static method
String.Format or instance methods
double.ToString
and
float.ToString.
Digits after decimal point
This example formats double to string with
fixed number of decimal
places. For two decimal places use pattern „
0.00“. If a
float number has less decimal places, the rest digits on the right will be
zeroes. If it has more decimal places, the number will be rounded.
[C#]
String.Format("{0:0.00}", 123.4567);
String.Format("{0:0.00}", 123.4);
String.Format("{0:0.00}", 123.0);
Next example formats double to string with
floating number of decimal
places. E.g. for maximal two decimal places use pattern
„
0.##“.
[C#]
String.Format("{0:0.##}", 123.4567);
String.Format("{0:0.##}", 123.4);
String.Format("{0:0.##}", 123.0);
Digits before decimal point
If you want a float number to have any
minimal number of digits
before decimal point use N-times zero before decimal point. E.g.
pattern „
00.0“ formats a float number to string with at least two
digits before decimal point and one digit after that.
[C#]
String.Format("{0:00.0}", 123.4567);
String.Format("{0:00.0}", 23.4567);
String.Format("{0:00.0}", 3.4567);
String.Format("{0:00.0}", -3.4567);
Thousands separator
To format double to string
with use of thousands separator
use zero and comma separator before an usual float formatting pattern, e.g.
pattern „
0,0.0“ formats the number to use thousands separators and to
have one decimal place.
[C#]
String.Format("{0:0,0.0}", 12345.67);
String.Format("{0:0,0}", 12345.67);
Zero
Float
numbers between zero and one can be formatted in two
ways, with or without leading zero before decimal point. To format number
without a leading zero use
# before point. For example „
#.0“
formats number to have one decimal place and zero to N digits before decimal
point (e.g. „.5“ or „123.5“).
Following code shows
how can be formatted a zero (of
double type).
[C#]
String.Format("{0:0.0}", 0.0);
String.Format("{0:0.#}", 0.0);
String.Format("{0:#.0}", 0.0);
String.Format("{0:#.#}", 0.0);
Align numbers with spaces
To align float number
to the right use comma „
,“
option before the colon. Type comma followed by a number of spaces, e.g.
„
0,10:0.0“ (this can be used only in
String.Format method, not in
double.ToString
method). To align numbers
to the left use negative number of
spaces.
[C#]
String.Format("{0,10:0.0}", 123.4567);
String.Format("{0,-10:0.0}", 123.4567);
String.Format("{0,10:0.0}", -123.4567);
String.Format("{0,-10:0.0}", -123.4567);
Custom formatting for negative numbers and zero
If you need to use custom format for negative float numbers or zero, use
semicolon separator „
;“ to split pattern to
three sections. The first section formats positive numbers, the
second section formats negative numbers and the third section
formats zero. If you omit the last section, zero will be formatted using the
first section.
[C#]
String.Format("{0:0.00;minus 0.00;zero}", 123.4567);
String.Format("{0:0.00;minus 0.00;zero}", -123.4567);
String.Format("{0:0.00;minus 0.00;zero}", 0.0);
Some funny examples
As you could notice in the previous example, you can put any text into
formatting pattern, e.g. before an usual pattern „
my text
0.0“. You can even put any text between the zeroes, e.g.
„
0aaa.bbb0“.
[C#]
String.Format("{0:my number is 0.0}", 12.3);
String.Format("{0:0aaa.bbb0}", 12.3);
The following example formats a
Double value with the currency format specifier.
double value = 12345.6789;
Console.WriteLine(value.ToString("C", CultureInfo.CurrentCulture));
Console.WriteLine(value.ToString("C3", CultureInfo.CurrentCulture));
Console.WriteLine(value.ToString("C3",
CultureInfo.CreateSpecificCulture("da-DK")));
// The example displays the following output on a system whose
// current culture is English (United States):
// $12,345.68
// $12,345.679
// kr 12.345,679
