How to know if a double string is round-trip safe?

Question

I have a text representation of a double and want to know if it's safe to round-trip it to double and back. How do I know this if I also want to accept any kind of number-style of the input? Or how do I know if any precision is lost when a double-string is parsed with Double.Parse? Or how do I ToString a double to match the same format as another double-string? An answer to any of these questions would be a solution I think.

Answer 1

Use the R format specifier to convert the double to a string:

myDouble.ToString("R")

See The Round-trip ("R") Format Specifier on MSDN.

The round-trip ("R") format specifier guarantees that a numeric value that is converted to a string will be parsed back into the same numeric value. This format is supported only for the Single, Double, and BigInteger types.

(emphasis mine)