bash 为什么对两个大的二进制数进行异或会给出十进制输出？
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Why does XORing two large binary numbers give a decimal output?
提问by gp_xps
I am trying to XOR two large binary values. However,
我正在尝试对两个大的二进制值进行异或。然而，
echo ${hashArray[1]}
echo ${hashArray[2]}
echo $((${hashArray[1]} ^ ${hashArray[2]}))
gives:
给出：
10100100000111101011100001101110000110000100001000000111001001100010110000010010111101100110111001111100010010000000010101110111
00001110110000010110101101011011100101101000011100011101001101101010000100110001001110101101111100010001111010100011010000000100
4018181242766406943
Why does echo $((${hashArray[1]} ^ ${hashArray[2]}))output a decimal number? Shouldn't it be another large binary value?
为什么echo $((${hashArray[1]} ^ ${hashArray[2]}))输出一个十进制数？不应该是另一个大的二进制值吗？
回答by Thor
bashdoes have support for binary numbers, however your numbers are too big and will be truncated. Either do as manasuggests or split up the string or use a library that can handle arbitrary precision, e.g. perl's Math::BigInt comes to mind:
bash确实支持 binary numbers，但是您的数字太大并且会被截断。要么按照mana建议做，要么拆分字符串，要么使用可以处理任意精度的库，例如 perl 的 Math::BigInt 想到：
xor.pl
异或
use Math::BigInt;
$x = Math::BigInt->new("0b" . $ARGV[0]);
$y = Math::BigInt->new("0b" . $ARGV[1]);
print $x->bxor($y)->as_bin;
Assign the numbers to variables for convenience:
为方便起见，将数字分配给变量：
x=10100100000111101011100001101110000110000100001000000111001001100010110000010010111101100110111001111100010010000000010101110111
y=00001110110000010110101101011011100101101000011100011101001101101010000100110001001110101101111100010001111010100011010000000100
Run with:
运行：
perl xor.pl $x $y
Output:
输出：
0b10101010110111111101001100110101100011101100010100011010000100001000110100100011110011001011000101101101101000100011000101110011
回答by mana
Do it "bitwise" like that:
像这样“按位”做：
#!/bin/bash
a="101"
b="011"
out=""
for ((i=0; i < ${#a}; i++ )); do
out=${out}$((${a:$i:1} ^ ${b:$i:1}))
done
echo ${a} ^ ${b} = $out
output:
输出：
101 ^ 011 = 110
edit: The inputs need to have the same length!
编辑：输入需要具有相同的长度！
回答by V. Michel
Do bitwise with bc, firstly get the file logic.bc :
用bc按位做，首先得到文件 logic.bc ：
wget http://phodd.net/gnu-bc/code/logic.bc
Test xor()
测试异或（）
x=10100100000111101011100001101110000110000100001000000111001001100010110000010010111101100110111001111100010010000000010101110111
y=00001110110000010110101101011011100101101000011100011101001101101010000100110001001110101101111100010001111010100011010000000100
echo "ibase=2;obase=2;xor($x,$y)" | bc -l logic.bc
Result:
结果：
10101010110111111101001100110101100011101100010100011010000100001000110100100011110011001011000101101101101000100011000101110011
