Python

an immutable (can be modified) sequence of integers in the range 0 <=x < 256, the elements of a bytes object cannot be changed

#!/usr/bin/python

s = b'Hello World!'
print(s, type(s))

#!/usr/bin/python

s = 'Hello'

b = bytes(s, encoding = 'utf-8')

print(type(s), type(b)) # unicode, byte string
print(s, b) # Hello b'Hello'

print(b[0], b[1]) # 72 101

a mutable (can be modified) sequence of integers in the range 0 <=x < 256

Bytes and bytearrays are an efficient, byte-based form of strings

#!/usr/bin/python
 
# convert list to bytearray
arr = bytearray([97, 98, 99, 99]);
print(arr) # bytearray(b'abcc')
 
# convert bytearray to bytes
print(bytes(arr)); # b'abcc'
 
# modify elements
arr[0] = 10;
 
# access element
print(arr) # bytearray(b'\nbcc')
 
# slicing
print(arr[:2]); # bytearray(b'\nb')

#!/usr/bin/python
 
arr = bytearray("Café", "utf-8");
print(type(arr))
 
# convert to string
s = str(arr) # unicode
print(type(s), s); # unicode, bytearray(b'Caf\xc3\xa9')

u = arr.decode('utf-8')
print(type(u), u) # unicode, Café
 
#count
print(arr.count(b'a'));

# in
if 97 in arr:
    print('a in arr ...')

# concatenation
print(arr+bytearray(b'dddddddd'));

#conver to list
print(list(arr)); #[67, 97, 102, 195, 169]

#append
arr.append(97);
print(arr)

#delete
del arr[:2];
print(arr)

#insert
arr.insert(0, 98);
print(arr);

#replace
arr = arr.replace(b'b', b'c');
print(arr);

Bytes and Bytearray