Dispose a variable

Question

Wondering how I can dispose of a variable. If this is my code... string myCode = GetMyCode(); myCode.Dispose(); // this is what I am trying to do What is the best way of disposing this variable because I don't want it to stay in memory because of its sensitivity.

Vulpes · Answer

The best thing to do would be to zero out its memory once you've finished using it. You can do this quite easily using unsafe code but so you don't have to compile with the /unsafe switch on I'll show you another way which uses P/Invoke to call the API function RtlZeroMemory: using System; using System.Runtime.InteropServices; class Program { [DllImport(Kernel32.dll EntryPoint=RtlZeroMemory)] static extern void ZeroMemory(IntPtr dest int size); static void Main() { string myCode = password; Console.WriteLine(myCode contains {0} myCode); GCHandle gch = GCHandle.Alloc(myCode GCHandleType.Pinned); int size = myCode.Length * 2; ZeroMemory(gch.AddrOfPinnedObject() size); gch.Free(); Console.WriteLine(myCode now contains {0} myCode); Console.ReadKey(true); } } The output is: myCode contains password myCode now contains There's also something called a SecureString but whether it would be suitable here depends on how the string is being constructed in the first place. Check out: http://msdn.microsoft.com/en-us/library/system.security.securestring(v=vs.110).aspx