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How to: Obtain the Address of a Variable (C# Programming Guide)

To obtain the address of a unary expression, which evaluates to a fixed variable, use the address-of operator:

int number;
int* p = &number; //address-of operator &

The address-of operator can only be applied to a variable. If the variable is a moveable variable, you can use the fixed statement to temporarily fix the variable before obtaining its address.

It is your responsibility to ensure that the variable is initialized. The compiler will not issue an error message if the variable is not initialized.

You cannot get the address of a constant or a value.

In this example, a pointer to int, p, is declared and assigned the address of an integer variable, number. The variable number is initialized as a result of the assignment to *p. If you make this assignment statement a comment, the initialization of the variable number will be removed, but no compile-time error is issued. Notice the use of the Member Access operator -> to obtain and display the address stored in the pointer.

// compile with: /unsafe
class AddressOfOperator
{
    static void Main()
    {
        int number;

        unsafe 
        {
            // Assign the address of number to a pointer: 
            int* p = &number;

            // Commenting the following statement will remove the 
            // initialization of number.
            *p = 0xffff;

            // Print the value of *p:
            System.Console.WriteLine("Value at the location pointed to by p: {0:X}", *p);

            // Print the address stored in p:
            System.Console.WriteLine("The address stored in p: {0}", (int)p);
        }

        // Print the value of the variable number:
        System.Console.WriteLine("Value of the variable number: {0:X}", number);

        System.Console.ReadKey();
    }
}
/* Output:
        Value at the location pointed to by p: FFFF
        The address stored in p: 2420904
        Value of the variable number: FFFF
*/
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