Appendix D. Data Marshaling
When calling between the runtime environment and existing COM interfaces, the CLR performs automatic data marshaling for CLR types into compatible COM types.
Table 4.1 describes the C# to COM default data type mapping.
Table D-1. C# Type to COM Type Mapping
C# Type |
COM Type |
---|---|
bool |
VARIANT_BOOL |
char |
unsigned short |
sbyte |
Char |
byte |
Unsigned char |
short |
Short |
ushort |
Unsigned short |
int |
Int |
uint |
Unsigned int |
long |
Hyper |
ulong |
Unsigned hyper |
float |
Single |
double |
Double |
decimal |
DECIMAL |
object |
VARIANT |
string |
BSTR |
System.DateTime |
|
System.Guid |
GUID |
System.Currency |
CURRENCY |
1-dimensional arrays |
SAFEARRAY |
Value types |
Equivalently named struct |
enum |
Equivalently named enum |
interface |
Equivalently named interface |
class |
Equivalently named |
[a] COM dates are less precise, causing comparison problems. |
Table 4.2 shows the mapping of the C# modifiers to their equivalent COM interface attributes.
Table D-2. C# Modifier/COM Attribute Mapping
C# Modifier |
COM Attribute |
---|---|
< |
[in] |
out |
[out] |
ref |
[in, out] |
< |
[out, retval] |
Get C# Essentials now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.