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How do you reverse a string in place in C or C++?
...tead of the end-finding loop.
(Editor's note: this answer originally used XOR-swap for this simple version, too. Fixed for the benefit of future readers of this popular question. XOR-swap is highly not recommended; hard to read and making your code compile less efficiently. You can see on the Go...
How to toggle a value in Python
...5
>>> x = total - x # toggle
>>> x
3
Solution using XOR
If the value toggles between 0 and 1, you can use a bitwise exclusive-or:
>>> x = 1
>>> x ^= 1
>>> x
0
>>> x ^= 1
>>> x
1
The technique generalizes to any pair of integers....
What are bitwise operators?
...ns
00000001
which is not 0, so the flag does specify READ.
You can use XOR to toggle various bits. I've used this when using a flag to specify directional inputs (Up, Down, Left, Right). For example, if a sprite is moving horizontally, and I want it to turn around:
Up: 00000001
Down: ...
Why can't (or doesn't) the compiler optimize a predictable addition loop into a multiplication?
... test esi, esi
jle .LBB0_1
mov r9d, esi
xor r8d, r8d
xor esi, esi
xor eax, eax
.LBB0_4: # =>This Inner Loop Header: Depth=1
movsxd rdx, dword ptr [rdi + 4*rsi]
imul rcx, rdx, 100000
...
Is there a way to create multiline comments in Python?
... elif token == '\\or':
do_something_else()
elif token == '\\xor':
'''
Note that we still need to provide support for the deprecated
token \xor. Hopefully we can drop support in libfoo 2.0.
'''
do_a_different_thing()
else:
raise Valu...
techniques for obscuring sensitive strings in C++
...e sure that the key is not within the printable range.
Obscuring key with XOR
For instance, you could use XOR to split the key into two byte arrays:
key = key1 XOR key2
If you create key1 with the same byte-length as key you can use (completely) random byte values and then compute key2:
key1[n...
How does this milw0rm heap spraying exploit work?
...add edx,esp
00000019 07 pop es
0000001A 67305CFF xor [si-0x1],bl
0000001E 98 cwde
0000001F BBD7FFA4FE mov ebx,0xfea4ffd7
00000024 9B wait
00000025 74AD jz 0xffffffd4
00000027 058B8B028D add eax,0x8d028b8b
0000002...
What does value & 0xff do in Java?
... ;//(.....000110)
onWhichThisHasTobeReSet &= thirdBitTobeReSet;
XOR
Just note that if you perform XOR operation twice, will results the same value.
byte toBeEncrypted = 0010 0110
byte salt = 0100 1011
byte encryptedVal = toBeEncrypted ^ salt == 0110 1101
byte decryptedV...
Why is a boolean 1 byte and not 1 bit of size?
...write code where I'd pack flags like that and then write "if flags & 0x110 != 0 then" or the like, but this is cryptic and these days I generally make separate fields and write "if fooFlag || barFlag" instead. I wouldn't rule out the possibility of cases where packing flags like that is better f...
How to implement a good __hash__ function in python [duplicate]
...more expensive than it needs to be.
Edit: I would recommend against using xor to mix hashes in general. When two different properties have the same value, they will have the same hash, and with xor these will cancel eachother out. Tuples use a more complex calculation to mix hashes, see tuplehash i...