DateTime.ToString() format that can be used in a filename or extension?

Question

I want to add a timestamp to filenames as files are created but most of the DateTime methods I\'ve tried output something with spaces and slashes. For instance:

Answer 1

Using interpolation string & format specifier:

var filename = $"{DateTime.Now:yyyy.dd.M HH-mm-ss}"

Example Output for January 1st, 2020 at 10:40:45AM:

2020.28.01 10-40-45

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Or if you want a standard date format:

var filename = $"{DateTime.Now:yyyy.M.dd HH-mm-ss}"

2020.01.28 10-40-45

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Note: this feature is available in C# 6 and later versions of the language.