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Compiler Error CS0212 

Error Message

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

For more information, see Unsafe Code and Pointers (C# Programming Guide).

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 mf() { 
      A a = new A();
      int* ptr = &a.iField;   // CS0212 

   // OK
   unsafe public void mf2() {
      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 mf()
      // 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);
      // }