# Bitwise NOT Operator for Sage?

0b1000 & 0b1001 (AND) 0b1000 | 0b1001 (OR) 0b1000 ^^ 0b1001 (XOR)

All of these work as bitwise operators on the command line -- but how do I do bitwise NOT?

Bitwise NOT Operator for Sage?

0b1000 & 0b1001 (AND) 0b1000 | 0b1001 (OR) 0b1000 ^^ 0b1001 (XOR)

All of these work as bitwise operators on the command line -- but how do I do bitwise NOT?

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3

The bitwise `not`

in Python is supposed to be `~`

(see https://wiki.python.org/moin/BitwiseO... about how negative numbers are encoded), but Sage's preparser first transforms `0b1000`

as an element of `ZZ`

for which the action of `~`

is the multiplicative inverse:

```
sage: ~0b1000
1/8
```

This is because, in Sage:

```
sage: 0b1000.parent()
Integer Ring
sage: preparse("0b1000")
"Integer('1000', 2)"
```

To get the python behaviour, you can either turn the sage preparser off:

```
sage: preparser(False)
sage: ~0b1000
-9
```

or explicitely use python `int`

:

```
sage: ~int(0b1000)
-9
```

Another workaround is to notice that `not a`

is the same as `a xor 1`

.

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Asked: ** 2014-08-18 23:30:28 +0200 **

Seen: **2,364 times**

Last updated: **Aug 20 '14**

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