Chapter 25 Unsafe code

1code to take the address of a local variable, value parameter, or parameter array which has been captured by

2an anonymous method.

325.5.5 Pointer increment and decrement

4In an unsafe context, the ++ and -- operators (§14.5.9 and §14.6.5) can be applied to pointer variables of all

5types except void*. Thus, for every pointer type T*, the following operators are implicitly defined:

6T* operator ++(T* x);

7T* operator --(T* x);

8The operators produce the same results as x+1 and x-1, respectively (§25.5.6). In other words, for a pointer

9variable of type T*, the ++ operator adds sizeof(T) to the address contained in the variable, and the

10-- operator subtracts sizeof(T) from the address contained in the variable.

11If a pointer increment or decrement operation overflows the domain of the pointer type, the result is

12implementation-defined, but no exceptions are produced.

1325.5.6 Pointer arithmetic

14In an unsafe context, the + operator (§14.7.4) and – operator (§14.7.5) can be applied to values of all

15pointer types except void*. Thus, for every pointer type T*, the following operators are implicitly defined:

16T* operator +(T* x, int y);

17T* operator +(T* x, uint y);

18T* operator +(T* x, long y);

19T* operator +(T* x, ulong y);

20T* operator +(int x, T* y);

21T* operator +(uint x, T* y);

22T* operator +(long x, T* y);

23T* operator +(ulong x, T* y);

24T* operator –(T* x, int y);

25T* operator –(T* x, uint y);

26T* operator –(T* x, long y);

27T* operator –(T* x, ulong y);

28long operator –(T* x, T* y);

29Given an expression P of a pointer type T* and an expression N of type int, uint, long, or ulong, the

32type T* that results from subtracting N * sizeof(T) from the address given by P.

33Given two expressions, P and Q, of a pointer type T*, the expression P – Q computes the difference

34between the addresses given by P and Q and then divides that difference by sizeof(T). The type of the

35result is always long. In effect, P - Q is computed as ((long)(P) - (long)(Q)) / sizeof(T).

36[Example:

37using System;

38class Test

39{

48}

49}

50which produces the output:

389