Format a number to always have a sign and decimal separator [duplicate]

Question

I want to format any number (integer or real) to a string representation which always has a sign (positive or negative) and a decimal separator, but no trailing zeroes.

Some samples:

3.14 => +3.14
12.00 => +12.
-78.4 => -78.4
-3.00 => -3.

Is it possible with one of the default ToString() implementations, or do I need write this myself?

Answer 1

Try something like this:

double x = -12.43;
string xStr = x.ToString("+0.#####;-0.#####");

But this wouldn't help to display trailing decimal point. You can handle such situations using this method:

public static string MyToString(double x)
{
    return x == Math.Floor(x)
        ? x.ToString("+0;-0;0") + CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator
        : x.ToString("+0.####;-0.####");
}