不能使用 fixed语句获得已固定的表达式的地址？这是怎么回事？

[appletan]

using System;
public class addrsOpr
{
unsafe public static int Main(string[] args)
{
// addrsOpr.cs
// A C# program demonstrating how to use
// the Binary AND operator & to return
// the address of an unsafe value
// PROGRAM DOES NOT COMPILE - erad last comment!!!
// Copyright (c) Chris H. Pappas and William H. Murray, 2001
//

Console.WriteLine("& used on true AND true = {0}", true & true);
Console.WriteLine("& used on true AND false = {0}", true & false);

int iValue = 4;

// the following "fixed" block IS crrect - hower,
// the program will NOT compile - WHY?
fixed(int *pi = &iValue)
{
string hexAddress = int.Format((int)pi, "x");
Console.WriteLine("& returning address of iValue: {0}", hexAddress);

// or the simpler version, not using teh string variable
Console.WriteLine("& returning address of iValue: {0}", int.Format((int)pi, "x"));
}

// to get addrsOpr.cs to compile and execute
// your MUST remember - ANY method using unsafe pointers
// must include the "unsafe" keyword in the method prototype
// when you change Main()'s prototype to:
// unsafe public static int Main(string[] args)
// the program will compile and execute!

return 0;
}
}

[lw8122]

I corrected your code. You can try to compile it again.
Don't forget set project option "allow unsafe code" to "true"


using System;
public class addrsOpr
{
int iValue = 4;

unsafe public static int Main(string[] args)
{
// addrsOpr.cs
// A C# program demonstrating how to use
// the Binary AND operator & to return
// the address of an unsafe value
// PROGRAM DOES NOT COMPILE - erad last comment!!!
// Copyright (c) Chris H. Pappas and William H. Murray, 2001
//

Console.WriteLine("& used on true AND true = {0}", true & true);
Console.WriteLine("& used on true AND false = {0}", true & false);


// the following "fixed" block IS crrect - hower,
// the program will NOT compile - WHY?
fixed(int *pi = &iValue)
{
string hexAddress = ((int)pi).ToString("x");
Console.WriteLine("& returning address of iValue: {0}", hexAddress);

// or the simpler version, not using teh string variable
Console.WriteLine("& returning address of iValue: {0}", ((int)pi).ToString("x"));
}

// to get addrsOpr.cs to compile and execute
// your MUST remember - ANY method using unsafe pointers
// must include the "unsafe" keyword in the method prototype
// when you change Main()'s prototype to:
// unsafe public static int Main(string[] args)
// the program will compile and execute!

return 0;
}
}