The /unsafe compiler option allows code that uses the unsafe keyword to compile.
For more information about unsafe code, see Unsafe Code and Pointers.
To set this compiler option in the Visual Studio development environment
Open the project's Properties page.
Click the Build property page.
Select the Allow Unsafe Code check box.
For information about how to set this compiler option programmatically, see AllowUnsafeBlocks.
in.cs for unsafe mode:
csc /unsafe in.cs