A detailed explanation of the FormatDateTime function for date formatting.

The FormatDateTime function is commonly used in many programming languages and frameworks to format dates and times into specified strings. It typically takes two parameters: the date and time to be formatted, and a format string that specifies the desired date and time format.

Here are some commonly used format strings and their corresponding output results:

1. “yyyy-MM-dd”: Display the year, month, and day of the date.
2. “HH:mm:ss”：displaying the hours, minutes, and seconds of the time.
3. “yyyy-MM-dd HH:mm:ss”: Display the year, month, day, hour, minute, and second of the date and time.
4. “EEE, MMM d, ”yy”: Displaying the abbreviated form of the day of the week, month, day, and last two digits of the year.
5. “yyyy-MM-dd’T’HH:mm:ss.SSSZ”: Display the date and time format in accordance with the ISO 8601 standard.

In addition to the standard format strings mentioned above, it is also possible to customize format strings to meet specific needs. Here are some commonly used custom format strings:

1. “MMM”: Displays the abbreviated form of the month (e.g. Jan, Feb).
2. “MMMM”: display the full name form of the month (such as: January, February).
3. “dd”: This outputs the date in a two-digit format (e.g. 01, 02, 31).
4. “HH”: Output the two-digit form of the hour (e.g. 01, 02, 23).
5. “mm” will display the minutes in a two-digit format (e.g. 01, 02, 59).
6. “ss”: output the two-digit form of seconds (for example: 01, 02, 59).

To use the FormatDateTime function, you can follow these steps:

1. Confirm the date and time to be formatted.
2. Specify the desired date and time format.
3. Passing the date, time, and format string as arguments to the FormatDateTime function.
4. Get the formatted string returned.

For example, to format the current date and time using the FormatDateTime function in C#, you can use the following code:

string formattedDateTime = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
Console.WriteLine(formattedDateTime);

The code above will display the year, month, day, hours, minutes, and seconds of the current date and time.

Please note that different programming languages and frameworks may have slightly different implementations of the FormatDateTime function, but the basic usage and definition of format strings are usually similar. Therefore, when using it, it is recommended to consult relevant documentation or refer to official documentation to understand the specific usage and supported format strings.