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Function HiByte
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Returns the HiByte (the most significant byte) from a 2-byte Word (aka Integer).
See also LoByte.
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A trivial task it seems, however, when you search for HiByte in the internet you'll find more wrong than right solutions. Here are two ubiquitous crap codes:
Public Function X01HiByte(ByVal Word As Integer)
' fails eg. at Word = &H8000
X01HiByte = Word \ &H100
End Function
Public Function X02HiByte(ByVal Word As Integer)
' fails eg. at Word = &HFFFF
X02HiByte = Word \ &H100& And &HFF&
End Function
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| Code |
| HiByte01 |
Public Function HiByte01(ByVal Word As Integer) As Byte
' by Donald, donald@xbeat.net, 20011202
HiByte01 = (Word And &HFF00&) \ &H100
End Function
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| HiByte02 |
Public Function HiByte02(ByVal Word As Integer) As Byte
' by Donald, donald@xbeat.net, 20011202
CopyMemory HiByte02, ByVal VarPtr(Word) + 1, 1
End Function
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| HiByte03 |
Public Function HiByte03(ByVal Word As Integer) As Byte
' by Anonymous, found at http://www.vbapi.com/ref/h/hibyte.html, 20011202
HiByte03 = Val("&H" & Left(Right("0000" & Hex(Word), 4), 2))
End Function
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| Calls |
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1 | bRet = HiByte(&H1234)
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| Charts |
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| VB5 Charts |
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| Call 1 |
| 1 | 1.00 | 0.049µs |
| 2 | 8.53 | 0.417µs |
| 3 | 238.37 | 11.651µs |
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| VB6 Charts |
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| Call 1 |
| 1 | 1.00 | 0.049µs |
| 2 | 9.37 | 0.458µs |
| 3 | 230.02 | 11.236µs |
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| Conclusions |
HiByte02: say no to dope!
HiByte03: I didn't include this gem to diss anybody: although it's more than 200 times slower than necessary it sure earns its credits since it packs a record number of performance sins into one line (and still works 100% correct). This is real cool.
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 Got comments? |
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