How to format a decimal without trailing zeros

Question

I've just learned that a decimal somehow remembers how much trailaing zero's were needed to store a number. With other words: it remembers the size of the fraction.

For example:

123M.ToString() ==> resuls in: 123
123.00M.ToString() ==> resuls in: 123.00
123.450M.ToString() ==> resuls in: 123.450

I am looking for a formatting string or another trick to get rid of those "unneeded" trailing zeros, but keeping the significant digits. So:

123M.ToString() ==> resuls in: 123
123.00M.ToString() ==> resuls in: 123
123.450M.ToString() ==> resuls in: 123.45

Removing the zeros at the end of the new string is not a real option for me, because then I have to find out if the string contains a fraction and if so, also have to remove the optional '.' or ',' depending on the culture, etc.

I think the best answer on this topic is [this one](http://stackoverflow.com/a/7983330/187697) — keyboardP, Jul 07 '13 at 21:21
Possible duplicate of [Remove trailing zeros](http://stackoverflow.com/questions/4525854/remove-trailing-zeros), which is older and has better answers and comments. — Sam, Feb 22 '17 at 00:57

score 16 · Accepted Answer · edited Oct 13 '19 at 23:48

16

There are several ways to do it, but since you are converting to a String object anyway, I suppose you could try something like this:

myDecimalVariable.ToString("G29");

or, using your code above, assuming 123.00M is your decimal:

123.00M.ToString("G29");

Here is the explanation of how that concise example works:

The G format with a number means to format that many significant digits. Because 29 is the most significant digits that a Decimal can have, this will effectively truncate the trailing zeros without rounding.

edited Oct 13 '19 at 23:48

Dan Beaulieu

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answered Jul 07 '13 at 21:19

Michael Hawkins

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See [this comment](http://stackoverflow.com/questions/4525854/remove-trailing-zeros/4525896#comment8733932_4525983) with regards to some cases where G29 might not work as expected. – keyboardP Jul 07 '13 at 21:21
Right, but his example didn't include any of those cases, so I figured it would be the easiest way to get what he wants. But that is good to know. – Michael Hawkins Jul 07 '13 at 21:22
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You're answer's not wrong but I thought it might be worth mentioning in case someone else comes across this thread. – keyboardP Jul 07 '13 at 21:23
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I definitely agree. Thanks. – Michael Hawkins Jul 07 '13 at 21:24
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And `"G0"` works the same way. See [Standard Numeric Format Strings - The General ("G") Format Specifier](http://msdn.microsoft.com/en-us/library/dwhawy9k.aspx#GFormatString). – Jeppe Stig Nielsen Jul 07 '13 at 22:10
4.98 gives 4.9800000000000004! – Ian Warburton Nov 23 '17 at 12:59
This prints 123 for `123M` and `123.00M`. This may be or may not be important depending on your needs :) – tymtam Oct 14 '19 at 01:32

terrybozzio · Answer 2 · 2013-07-07T22:02:31.677

0

just apply the Format specifier zero and will remove the trailing zeros:

string test = (1.23M * 100M).ToString("0");
//prints 123.
string test2 = 123.450M.ToString(".00");
//prints 123.45.
string test3 = 123.450M.ToString().Trim('0');

edited Jul 07 '13 at 22:02

answered Jul 07 '13 at 21:36

terrybozzio

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Note that `Trim('0')` will result in `0.5m` being formatted as `.5` rather than `0.5`. – Sam Feb 22 '17 at 00:30

tymtam · Answer 3 · 2019-10-14T01:43:55.433

The method below () deals with the following edge cases:

Input: 123.00M, expecting "123.00"
- ❌ G29: 123
- ✅ : 123.00
Input: -0.00000000001M, expecting "-0.00000000001"
- ❌ G29: -1E-11
- ✅ : -0.00000000001

private static string SlowButStrong(decimal v)
{
  if( v % 1 == 0) return v.ToString(); // If no decimal digits, let's leave it alone
  var withNoZeroes = v.ToString().TrimEnd('0');
  return withNoZeroes.EndsWith('.') ? withNoZeroes + "00" : withNoZeroes;
}

Test output

Input 123M, expecting 123
✅ G29: 123
✅ : 123
✅ ⛵: 123

Input 123.00M, expecting 123.00
❌ G29: 123
✅ : 123.00
❌ ⛵: 123

Input 123.45M, expecting 123.45
✅ G29: 123.45
✅ : 123.45
✅ ⛵: 123.45

Input 123.450M, expecting 123.45
✅ G29: 123.45
✅ : 123.45
✅ ⛵: 123.45

Input 5.00000001M, expecting 5.00000001
✅ G29: 5.00000001
✅ : 5.00000001
✅ ⛵: 5.00000001

Input -0.00000000001M, expecting -0.00000000001
❌ G29: -1E-11
✅ : -0.00000000001
✅ ⛵: -0.00000000001

Input 10000000000000000000000M, expecting 10000000000000000000000
✅ G29: 10000000000000000000000
✅ : 10000000000000000000000
✅ ⛵: 10000000000000000000000

Arbitrary test case

public static void Main(string[] args)
{
    Test("123M", 123M, "123");
    Test("123.00M", 123.00M, "123.00");
    Test("123.45M", 123.45M, "123.45");
    Test("123.450M", 123.450M, "123.45");
    Test("5.00000001M", 5.00000001M, "5.00000001");
    Test("-0.00000000001M", -0.00000000001M, "-0.00000000001");
    Test("10000000000000000000000M", 10000000000000000000000M, "10000000000000000000000");
}

private static void Test(string vs, decimal v, string expected)
{
    Console.OutputEncoding = System.Text.Encoding.UTF8;

    Console.WriteLine($"Input {vs}, expecting {expected}");
    Print("G29", v.ToString("G29"), expected);
    Print("", SlowButStrong(v), expected);
    Print("⛵", LessSlowButStrong(v), expected);
    Console.WriteLine();
}

private static void Print(string prefix, string formatted, string original)
{
    var mark = formatted == original ? "✅" : "❌"; 
    Console.WriteLine($"{mark} {prefix:10}: {formatted}");
}

private static string SlowButStrong(decimal v)
{
    if( v % 1 == 0) return v.ToString(); // If no decimal digits, let's leave it alone
    var withNoZeroes = v.ToString().TrimEnd('0');
    return withNoZeroes.EndsWith('.') ? withNoZeroes + "00" : withNoZeroes;
}

private static string LessSlowButStrong(decimal v)
{
    return v.ToString((v < 1) ? "" : "G29");
}

How to format a decimal without trailing zeros

3 Answers3

Test output

Arbitrary test case

Linked