Move/Rename File

 Dim fi As New FileInfo("myOldName.txt")
fi.MoveTo("myNewName.txt")

Calculate File Size

Imports System.IO

Private Function GetFileSize(ByVal MyFilePath As String) As Long

Dim MyFile As New FileInfo(MyFilePath)
Dim FileSize As Long = MyFile.Length
Return FileSize

End Function

DateTime Formats

d - Numeric day of the month without a leading zero.
dd - Numeric day of the month with a leading zero.
ddd - Abbreviated name of the day of the week.
dddd - Full name of the day of the week.

f,ff,fff,ffff,fffff,ffffff,fffffff - Fraction of a second. The more F's the higher the presision.

h - 12 Hour clock, no leading zero.
hh - 12 Hour clock with leading zero.
H - 24 Hour clock, no leading zero.
HH - 24 Hour clock with leading zero.

m - Minutes with no leading zero.
mm - Minutes with leading zero.

M - Numeric month with no leading zero.
MM - Numeric month with a leading zero.
MMM - Abbreviated name of month.
MMMM - Full month name.

s - Seconds with no leading zero.
ss - Seconds with leading zero.

t - AM/PM but only the first letter.
tt - AM/PM

y - Year with out century and leading zero.
yy - Year with out century, with leading zero.
yyyy - Year with century.

zz - Time zone off set with +/-.

String to DateTime conversion and Vice Versa

'String to DateTime

VB.Net
Dim dateString As String
dateString = "1999-09-01 21:34 PM"
Dim datetimeStamp As New DateTime
datetimeStamp = DateTime.ParseExact(dateString, "yyyy-MM-dd HH:mm tt", Nothing)

C#
// String to DateTime
String MyString;
MyString = "1999-09-01 21:34 PM";
DateTime MyDateTime;
MyDateTime = new DateTime();
MyDateTime = DateTime.ParseExact(MyString, "yyyy-MM-dd HH:mm tt", null);

VB.Net
'DateTime to String
datetimeStamp = New DateTime(1999, 9, 1, 21, 34, 0)
dateString = datetimeStamp.ToString("yyyy-MM-dd HH:mm tt")

C#
//DateTime to String
MyDateTime = new DateTime(1999, 09, 01, 21, 34, 00);
String MyString;
MyString = MyDateTime.ToString("yyyy-MM-dd HH:mm tt");