count in Python

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*Memo for a string and byte string(bytes and bytearray) functions:

• My post explains index().
• My post explains rindex().
• My post explains find().
• My post explains rfind().
• My post explains ord(), sorted() and reversed().

*Memo for a string and byte string(bytes and bytearray):

• My post explains a string.
• My post explains a byte string.

str.count() and bytes.count() or bytearray.count() can count the substrings and byte substrings respectively matched to sub between [start, end) as shown below:

*Memo:

• The 1st argument is sub(Required-Type:str for str.count() or Bytes-like object and int for bytes.count() and bytearray.count()):
  • It's the substring and byte substring of zero or more characters and bytes respectively.
  • Don't use sub=.
• The 2nd argument is start(Optional-Type:int or NoneType):
  • It's a start index(inclusive).
  • If it's not set or None, 0 is set to it.
  • Don't use start.
• The 3rd argument is end(Optional-Type:int or NoneType):
  • It's an end index(exclusive).
  • If it's not set or None, the length + 1 is set to it.
  • Don't use end.
• The length + 1 is returned if sub is an empty string and byte string respectively and if start and end aren't set.

<String>:

v = 'hello world'

print(v.count('l'))
print(v.count('l', None, None))
# 3

print(v.count('o'))
# 2

print(v.count('d'))
# 1

print(v.count('l', 3))
print(v.count('l', 3, 11))
# 2

print(v.count('l', 3, 9)) 
# 1

print(v.count('L'))
print(v.count('a'))
# 0

print(v.count('ll'))
print(v.count('lo'))
print(v.count('wo'))
# 1

print(v.count(''))
print(v.count('', 0, 11))
# 12

print(v.count('', 0, 4))
print(v.count('', 3, 7))
print(v.count('', 7, 11))
# 5

v = ''

print(v.count('')) # 1

<Byte String(bytes & bytearray)>:

v = b'hello world'
v = bytearray(b'hello world')

print(v.count(b'l'))
print(v.count(ord('l')))
print(v.count(108))
print(v.count(bytearray(b'l')))
print(v.count(b'l', None, None))
print(v.count(ord('l'), None, None))
print(v.count(108, None, None))
print(v.count(bytearray(b'l'), None, None))
# 3

print(v.count(b'o'))
print(v.count(ord('o')))
print(v.count(111))
print(v.count(bytearray(b'o')))
# 2

print(v.count(b'd'))
print(v.count(ord('d')))
print(v.count(100))
print(v.count(bytearray(b'd')))
# 1

print(v.count(b'l', 3))
print(v.count(ord('l'), 3))
print(v.count(108, 3))
print(v.count(bytearray(b'l'), 3))
print(v.count(b'l', 3, 11))
print(v.count(ord('l'), 3, 11))
print(v.count(108, 3, 11))
print(v.count(bytearray(b'l'), 3, 11))
# 2

print(v.count(b'l', 3, 9))
print(v.count(ord('l'), 3, 9))
print(v.count(108, 3, 9))
print(v.count(bytearray(b'l'), 3, 9))
# 1

print(v.count(b'L'))
print(v.count(ord('L')))
print(v.count(76))
print(v.count(bytearray(b'L')))
print(v.count(b'a'))
print(v.count(ord('a')))
print(v.count(97))
print(v.count(bytearray(b'a')))
# 0

print(v.count(b'll'))
print(v.count(bytearray(b'll')))
print(v.count(b'lo'))
print(v.count(bytearray(b'lo')))
print(v.count(b'wo'))
print(v.count(bytearray(b'wo')))
# 1

print(v.count(b''))
print(v.count(bytearray(b'')))
print(v.count(b'', 0, 11))
print(v.count(bytearray(b''), 0, 11))
# 12

print(v.count(b'', 0, 4))
print(v.count(bytearray(b''), 0, 4))
print(v.count(b'', 3, 7))
print(v.count(bytearray(b''), 3, 7))
print(v.count(b'', 7, 11))
print(v.count(bytearray(b''), 7, 11))
# 5

v = b''
v = bytearray(b'')

print(v.count(b''))
print(v.count(bytearray(b'')))
# 1