Two's complement: Difference between revisions
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0b000000000000000001011000100110000111101010001001001010011</pre>
=={{header|Wren}}==
Strictly speaking, Wren doesn't have integers. Instead all numbers are 'IEEE 754' 64 bit floating point values (their underlying C type being ''double'') and negative numbers are therefore represented using the ''offset binary'' method rather than ''two's complement''.
This is illustrated by running the following code:
<lang ecmascript>var a = 0
a = -a
System.print(a) // -0</lang>
which produces 'negative zero' rather than just 'zero'.
However, when using the bitwise operators, Wren's VM emulates the corresponding operation in C by first converting the operands to ''unsigned'' 32 bit values, performing the operation and then converting the result back to a double.
We can therefore emulate how two's complement works on ''signed'' 32 bit integers by using the bitwise complement operator '''~''' to flip the bits as follows:
<lang ecmascript>var pow32 = 2.pow(32)
var pow31 = 2.pow(31)
var bs = [-pow31, -pow31+1, -2, -1, 0, 1, 2, pow31-2, pow31-1]
for (b in bs) {
var b2 = ~b + 1
if (b2 > pow31) b2 = b2 - pow32
System.print("%(b) -> %(b2)")
}</lang>
{{out}}
<pre>
-2147483648 -> 2147483648
-2147483647 -> 2147483647
-2 -> 2
-1 -> 1
0 -> 0
1 -> -1
2 -> -2
2147483646 -> -2147483646
2147483647 -> -2147483647
</pre>
=={{header|Z80 Assembly}}==
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