XOR 操作在 Python 中没有给出预期的 output

Question

Hi i would expect the value of "mask_inv" to be the inverted value of "mask_int"
Instead the output is: 11111111111111111111109836129268
Can anyone explain why and how I can fix this?

msb = 10
lsb = 2 

#mask32 [lsb:msb] = [0]  
#sli = mask32 [2:10]
#print (mask32)

mylist = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]

#create mask for the given field with lsb and msb
if msb != lsb:
    for i in range (lsb, msb):
        mylist [i] = 0
else:
    mylist [msb] = 0 

list.reverse(mylist)
mask_str = ''.join([str(elem) for elem in mylist])
mask_int = int(mask_str)


zero_32 = 2**32-1
print("%s"%"{:032b}".format(zero_32))
print (mask_int)
mask_inv = mask_int ^ zero_32
print (mask_inv)
#print("mask_inv: %s"%"{:032b}".format(mask_inv))

Answer 1

You need to work with ints as though their underlying storage is in binary (which it is of course):

zero_32 = 2**32-1
print("%s"%"{:032b}".format(zero_32), zero_32)

msb = 10
lsb = 2 

mask_int = zero_32
mask_bit = 2**lsb
for _ in range(lsb, msb):
    mask_int -= mask_bit
    mask_bit *= 2

print ("%s"%"{:032b}".format(mask_int), mask_int)
mask_inv = mask_int ^ zero_32
print ("%s"%"{:032b}".format(mask_inv), mask_inv)

Output:

11111111111111111111111111111111 4294967295
11111111111111111111110000000011 4294966275
00000000000000000000001111111100 1020