find in Python

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*Memo for string, bytes and bytearray functions:

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

*Memo for a string, bytes and bytearray:

• My post explains a string.
• My post explains a bytes.
• My post explains a bytearray.

str.find() and bytes.find() or bytearray.find() can get the 1st index of the substring and byte substring respectively matched to sub between [start, end), searching from the left to the right (without error even if the substring and byte substring don't exist respectively) as shown below:

*Memo:

• The 1st argument is sub(Required-Type:str for str.find() or Bytes-like object and int for bytes.find() and bytearray.find()):
  • 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.
• -1 is returned if sub doesn't exist.

<String>:

v = 'grapes peach'

print(v.find('pe'))             # 3
print(v.find('pe', None, None)) # 3
print(v.find('PE'))             # -1
print(v.find('pe', 3))          # 3
print(v.find('pe', 4))          # 7
print(v.find('pe', 7))          # 7
print(v.find('pe', 8))          # -1
print(v.find('pe', 0, 4))       # -1
print(v.find('pe', 0, 5))       # 3
print(v.find('pe', 7, 12))      # 7
print(v.find('pe', 8, 12))      # -1

print(v.find(''))          # 0
print(v.find('g', 0, 1))   # 0
print(v.find('h', 11, 12)) # 11
print(v.find('abc'))       # -1

v = ''

print(v.find('')) # 0

<Byte String(bytes & bytearray)>:

v = b'grapes peach'
v = bytearray(b'grapes peach')

print(v.find(b'pe'))                        # 3
print(v.find(bytearray(b'pe')))             # 3
print(v.find(b'pe', None, None))            # 3
print(v.find(bytearray(b'pe'), None, None)) # 3
print(v.find(b'PE'))                        # -1
print(v.find(bytearray(b'PE')))             # -1
print(v.find(b'pe', 3))                     # 3
print(v.find(bytearray(b'pe'), 3))          # 3
print(v.find(b'pe', 4))                     # 7
print(v.find(bytearray(b'pe'), 4))          # 7
print(v.find(b'pe', 7))                     # 7
print(v.find(bytearray(b'pe'), 7))          # 7
print(v.find(b'pe', 8))                     # -1
print(v.find(bytearray(b'pe'), 8))          # -1
print(v.find(b'pe', 0, 4))                  # -1
print(v.find(bytearray(b'pe'), 0, 4))       # -1
print(v.find(b'pe', 0, 5))                  # 3
print(v.find(bytearray(b'pe'), 0, 5))       # 3
print(v.find(b'pe', 7, 12))                 # 7
print(v.find(bytearray(b'pe'), 7, 12))      # 7
print(v.find(b'pe', 8, 12))                 # -1
print(v.find(bytearray(b'pe'), 8, 12))      # -1

print(v.find(b''))                     # 0
print(v.find(bytearray(b'')))          # 0
print(v.find(b'g', 0, 1))              # 0
print(v.find(ord('g'), 0, 1))          # 0
print(v.find(103, 0, 1))               # 0
print(v.find(bytearray(b'g'), 0, 1))   # 0
print(v.find(b'h', 11, 12))            # 11
print(v.find(ord('h'), 11, 12))        # 11
print(v.find(104, 11, 12))             # 11
print(v.find(bytearray(b'h'), 11, 12)) # 11
print(v.find(b'abc'))                  # -1
print(v.find(bytearray(b'abc')))       # -1

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

print(v.find(b''))            # 0
print(v.find(bytearray(b''))) # 0