DateTime格式-在C＃中获取System.FormatException

Question

I am very new to C#.. I am writing an appointment schedule program where in I want to provide Date and Time value as a string from console and then I want to parse it to DateTime format. But by doing so I am getting

"System.FormatException" - string was not recognized as a valid datetime

Here is my piece of code,

string Format = "dd/MM/yyyy hh:mm tt";
Console.WriteLine("Enter the appointment date and time in(dd/MM/yyyy hh:mm AM/PM) format");
User_Input = Console.ReadLine();
Date_Time = DateTime.ParseExact(User_Input,Format,CultureInfo.InvariantCulture);

When I provide input exactly as format ie like 23/11/2012 08:30 pm.. I am getting the said exception. I want to output datetime with AM/PM . What have I done wrong?

Answer 1

The question is a little bit odd since your format string works with your given input string(in all cultures) and you want to output with the same format. Perhaps somebody entered 23/11/2012 18:30 pm instead which does not work with the AM/PM designator.

string format = "dd/MM/yyyy hh:mm tt";
DateTime dateTime = DateTime.ParseExact("23/11/2012 08:30 pm", format, CultureInfo.InvariantCulture);
string output = dateTime.ToString(format, CultureInfo.InvariantCulture);

outputs: 23/11/2012 08:30 PM

demonstration

Note that you can always use DateTime.TryParseExact to validate user input.