Compiler Error CS0212

You can only take the address of an unfixed expression inside of a fixed statement initializer

For more information, see Unsafe Code and Pointers.

The following sample shows how to take the address of an unfixed expression. The following sample generates CS0212.

// CS0212a.cs  
// compile with: /unsafe /target:library  
  
public class A {  
   public int iField = 5;  
  
   unsafe public void M() {   
      A a = new A();  
      int* ptr = &a.iField;   // CS0212   
   }  
  
   // OK  
   unsafe public void M2() {  
      A a = new A();  
      fixed (int* ptr = &a.iField) {}  
   }  
}  

The following sample also generates CS0212 and shows how to resolve the error:

// CS0212b.cs  
// compile with: /unsafe /target:library  
using System;  
  
public class MyClass  
{  
   unsafe public void M()  
   {  
      // Null-terminated ASCII characters in an sbyte array   
      sbyte[] sbArr1 = new sbyte[] { 0x41, 0x42, 0x43, 0x00 };  
      sbyte* pAsciiUpper = &sbArr1[0];   // CS0212  
      // To resolve this error, delete the previous line and   
      // uncomment the following code:  
      // fixed (sbyte* pAsciiUpper = sbArr1)  
      // {  
      //    String szAsciiUpper = new String(pAsciiUpper);  
      // }  
   }  
}