The /unsafe compiler option allows code that uses the unsafe keyword to compile.
/unsafe
Remarks
For more information about unsafe code, see Unsafe Code and Pointers (C# Programming Guide).
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.
Example
Compile in.cs for unsafe mode:
csc /unsafe in.cs
See Also
Tasks
How to: Modify Project Properties and Configuration Settings