I want to perform a bitwise-AND operation in VB.NET, taking a Short (16-bit) variable and ANDing it with '0000000011111111' (thereby retaining only the least-significant byte / 8 least-significant bits).
How can I do it?
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Are you doing string concatenation or IF conditions? – DOK Oct 28 '10 at 19:25
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can you give psudo code of what you atempting? – Iain Oct 28 '10 at 19:26
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dim a as short ..... dim b as byte = doing and with a. – Barun Oct 28 '10 at 19:27
3 Answers
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0000000011111111 represented as a VB hex literal is &HFF (or &H00FF if you want to be explicit), and the ordinary AND operator is actually a bitwise operator. So to mask off the top byte of a Short you'd write:
shortVal = shortVal AND &HFF
For more creative ways of getting a binary constant into VB, see: VB.NET Assigning a binary constant
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@Barun: the leading 0s are superfluous. Use 'em if you want to... It makes no difference. – Shog9 Oct 28 '10 at 19:37
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Use the And operator, and write the literal in hexadecimal (easy conversion from binary):
theShort = theShort And &h00ff
If what you are actually trying to do is to divide the short into bytes, there is a built in method for that:
Dim bytes As Byte() = BitConverter.GetBytes(theShort)
Now you have an array with two bytes.
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result = YourVar AND cshort('0000000011111111')
bugtussle
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2Strings are delimited with quotation marks not apostrophes. The CShort function doesn't assume binary as base, but decimal, so trying to convert that string causes an overflow. – Guffa Oct 28 '10 at 19:34