Recently I was looking into some old VB6 code and for my own reference decided I’d put together a simple summary of how VB6 data types map to .NET data types.
This is nothing new, but I thought it would be handy to have a quick comparison chart available. I obtained the information for this chart directly from the MSDN VB6 and MSDN VB.NET documentation pages (see below for the reference links).
Here is the summary:
| VB 6.0 | VB 6.0 Bytes | VB 6.0 Range | VB.NET | VB.NET Bytes | VB.NET Range |
|---|---|---|---|---|---|
| Boolean | True/False | True/False | Boolean | True/False | True/False |
| Byte | 1 | 0-255 | Byte | 1 | 0-255 |
| — | — | — | Char | 2 | 0-65535 |
| Date | 8 | 0:00:00 0001-01-01 – 11:59:59 9999-12-31 | Date | 8 | 0:00:00 0001-01-01 – 11:59:59 9999-12-31 |
| Currency | 8 | -922,337,203,685,477.5808 to 922,337,203,685,477.5807 | Decimal | 16 | 0 to +/-79,228,162,514,264,337,593,543,950,335 or 0 to +/-7.9228162514264337593543950335 |
| Decimal | 14 | Decimal | 16 | ||
| Double | 8 | -1.79769313486231E308 to -4.94065645841247E-324 or 4.94065645841247E-324 to 1.79769313486232E308 |
Double | 8 | -1.79769313486231570E+308 through -4.94065645841246544E-324 or 4.94065645841246544E-324 through 1.79769313486231570E+308 |
| Integer | 2 | -32,768 – 32,767 | Integer | 4 | -2,147,483,648 – 2,147,483,647 |
| Long | 4 | -2,147,483,648 – 2,147,483,647 | Long | 8 | -9,223,372,036,854,775,808 – 9,223,372,036,854,775,807 |
| Variant | 4 | 22 bytes + string length | Object | 4 | 4 bytes on 32, 8 on 64 bit platform (+ the cost of the element being held by the object) |
| — | — | SByte | 1 | -128 through 127 | |
| — | — | Short | 2 | -32,768 through 32,767 | |
| Single | 4 | Single | 4 | -3.4028235E+38 to -1.401298E-45, 1.401298E-45 to 3.4028235E+38 | |
| String | Variable/Fixed | 10 bytes + string length | String | Variable | 0- 2 billion Unicode characters |
| — | — | UInteger | 4 | 0 – 4,294,967,295 | |
| — | — | ULong | 8 | 0 -18,446,744,073,709,551,615 | |
| — | — | UShort | 2 | 0 – 65,535 |
If you create a VB6 array, then the array itself will take 20 bytes plus 4 bytes for each dimension. Then any data added to the array will occupy the size of the element times the number of added elements (ie: 6 dates added to a 1-dimensional array would be (6 * 8 )+ 20 + 4 = 52 bytes used.
Alternately if you create a VB.NET array, the cost is 12 bytes + 8 bytes for each dimension on a 32 bit system, and 24 + 16 on a 64 bit system.
References:
Justin Cooney 