| Type ::= | Clause |
|---|---|
| … | |
| Type '&' |
II.14.4.2 |
| Type '*' |
II.14.4.1 |
A pointer type shall be defined by specifying a signature that includes the type of the location at which it points. A pointer can be managed (reported to the CLI garbage collector, denoted by &, see §II.14.4.2) or unmanaged (not reported, denoted by *, see §II.14.4.1)
Pointers can contain the address of a field (of an object or value type) or of an element of an array. Pointers differ from object references in that they do not point to an entire type instance, but, rather, to the interior of an instance. The CLI provides two type-safe operations on pointers:
-
Loading the value from the location referenced by the pointer.
-
Storing a value V into the location referenced by a pointer P, where the type of V is assignable-to (§I.8.7.3) the type referenced by P.
For pointers into the same array or object (see Partition I) the following arithmetic operations are supported:
-
Adding an integer value to a pointer (where that value is interpreted as a number of bytes), which results in a pointer of the same kind
-
Subtracting an integer value from a pointer (where that value is interpreted as a number of bytes), which results in a pointer of the same kind. Note that subtracting a pointer from an integer value is not permitted.
-
Two pointers, regardless of kind, can be subtracted from one another, producing an integer value that specifies the number of bytes between the addresses they reference.
The following is informative text.
Pointers are compatible with unsigned int32 on 32-bit architectures, and with unsigned int64 on 64-bit architectures. They are best considered as unsigned int, whose size varies depending upon the runtime machine architecture.
The CIL instruction set (see Partition III) contains instructions to compute addresses of fields, local variables, arguments, and elements of vectors:
| Instruction | Description |
|---|---|
ldarga |
Load address of argument |
ldelema |
Load address of vector element |
ldflda |
Load address of field |
ldloca |
Load address of local variable |
ldsflda |
Load address of static field |
Once a pointer is loaded onto the stack, the ldind class of instructions can be used to load the data item to which it points. Similarly, the stind family of instructions can be used to store data into the location.
Note that the CLI will throw an InvalidOperationException for an ldflda instruction if the address is not within the current application domain. This situation arises typically only from the use of objects with a base type of System.MarshalByRefObject (see Partition IV).