Binary Representation¶
Question¶
Write a program to display the binary representation of various integers.
Solution¶
#!/usr/bin/python
"""
Program to do binary representation of various interesting ints.
"""
def convert_to_binary(n):
binary = []
while n:
binary.append(str(n%2))
n/=2
binary.reverse()
return "".join(binary)
for i in range(20,30):
print i, convert_to_binary(i)
hexa_values = ['0','1','A','FF','DEADBEEF','CAFEBABE']
for each in hexa_values:
dec = int(each, 16)
print each, convert_to_binary(dec)
"""
Find out if the machine is storing it in the one's complement or two's
complement.
1 is stored as 0000 0001
-1 in 1's complement is 1111 1110
-1 in 2's complement is 1111 1111
"""
import struct
if (ord(struct.pack('b',-1)[0]) == 255):
print 'twos complement'
else:
print 'ones complement'
for i in range(200,255):
print hex(i)
for i in range(0,256):
print chr(i), i, hex(i)
"""
Binary Addition and Subtraction
"""
a = 20
b = 10
a_bin = convert_to_binary(a)
b_bin = convert_to_binary(b)
if (len(a_bin) > len(b_bin)):
b_bin = b_bin.rjust(len(a_bin),'0')
elif (len(a_bin) < len(b_bin)):
a_bin = a_bin.rjust(len(b_bin),'0')
def sum_bin(a, b):
rules = {('0', '0'):(0,0),
('0', '1'):(1,0),
('1', '0'):(1,0),
('1', '1'):(0,1)
}
carry = 0
sum = 0
result = ""
for x,y in zip(reversed(a),reversed(b)):
sum = rules[(x,y)][0]
if carry:
sum = rules[(str(sum), str(carry))][0]
result += str(sum)
carry = rules[(x,y)][1]
if carry:
result += str(1)
return result[::-1]
def sub_bin(a, b):
ones_complement = ""
for c in b:
if c == '0':
ones_complement += '1'
elif c == '1':
ones_complement += '0'
b = ones_complement
b = sum_bin(b,'1'.rjust(len(b),'0'))
rules = {('0', '0'):(0,0),
('0', '1'):(1,0),
('1', '0'):(1,0),
('1', '1'):(0,1)
}
carry = 0
sum = 0
result = ""
for x,y in zip(reversed(a),reversed(b)):
sum = rules[(x,y)][0]
if carry:
sum = rules[(str(sum), str(carry))][0]
result += str(sum)
carry = rules[(x,y)][1]
# unlike addition carry should be discarded.
return result[::-1]
print 'a', a, a_bin
print 'b', b, b_bin
print 'a+b ',sum_bin(a_bin, b_bin)
print 'a-b ',sub_bin(a_bin, b_bin)