C# double formatting align on decimal sign

Question

I align numbers with various number of decimals so that the decimal sign aligns on a straight row. This can be achevied by padding with spaces, but I'm having trouble.

Lays say I want to align the following numbers: 0 0.0002 0.531 2.42 12.5 123.0 123172

This is the result I'm after:

     0
     0.0002
     0.531
     2.42
    12.5
   123.0
123172

Answer 1

You can use string.format or ToString method of double to do so.

double MyPos = 19.95, MyNeg = -19.95, MyZero = 0.0;

string MyString = MyPos.ToString("$#,##0.00;($#,##0.00);Zero");

// In the U.S. English culture, MyString has the value: $19.95.

MyString = MyNeg.ToString("$#,##0.00;($#,##0.00);Zero");

// In the U.S. English culture, MyString has the value: ($19.95).
// The minus sign is omitted by default.

MyString = MyZero.ToString("$#,##0.00;($#,##0.00);Zero");

// In the U.S. English culture, MyString has the value: Zero.

this article from msdn can help you if you need more details

Answer 2

If you want exactly that result you can't use any formatting of numerical data, as that would not format 123 as 123.0. You have to treat the values as strings to preserve the trailing zero.

This gives you exactly the result that you asked for:

string[] numbers = { "0", "0.0002", "0.531", "2.42", "12.5", "123.0", "123172" };

foreach (string number in numbers) {
  int pos = number.IndexOf('.');
  if (pos == -1) pos = number.Length;
  Console.WriteLine(new String(' ', 6 - pos) + number);
}

Output:

     0
     0.0002
     0.531
     2.42
    12.5
   123.0
123172