Why can't DateTime.ParseExact() parse “9/1/2009” using “M/d/yyyy”
问题 I have a string that looks like this: \"9/1/2009\". I want to convert it to a DateTime object (using C#). This works: DateTime.Parse(\"9/1/2009\", new CultureInfo(\"en-US\")); But I don\'t understand why this doesn\'t work: DateTime.ParseExact(\"9/1/2009\", \"M/d/yyyy\", null); There\'s no word in the date (like \"September\"), and I know the specific format, so I\'d rather use ParseExact (and I don\'t see why CultureInfo would be needed). But I keep getting the dreaded \"String was not