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Super Kai (Kazuya Ito)
Super Kai (Kazuya Ito)

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String in Python (2)

#python #string #str #function

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*Memo:

str() can create a string with or without many types of values or can decode a byte string to a string as shown below:

*Memo:

  • The 1st argument is object(Optional-Default:''-Type:Any or Default: b''-Type:Bytes-like object):
    • If encoding and/or errors are/is set, it must be a bytes-like object to decode and its default value is b'', working as decode().
  • The 2nd argument is encoding(Optional-Default:'utf-8'-Type:str):
    • 'utf-8', 'utf-7', 'utf-16', 'big5', 'ascii', etc can be set to it.
    • You can see Standard Encodings for more possible values.
  • The 3rd argument is errors(Optional-Default:'strict'-Type:str):
    • It controls decoding error with the error handlers, 'strict', 'ignore', 'replace', 'xmlcharrefreplace', 'backslashreplace', etc.
    • 'strict' raises UnicodeError if the character or byte, which cannot be encoded or decoded, exists.
    • 'ignore' ignores the character or byte which cannot be encoded or decoded.
    • 'replace' replaces the character or byte, which cannot be encoded or decoded, with ? for encoding or � for decoding.
    • 'xmlcharrefreplace' replaces the character, which cannot be encoded, with the XML/HTML numeric character reference format &#num;:
      • It doesn't support decoding so error occurs for the byte which cannot be decoded while error doesn't occur for the byte which can be decoded.
    • 'backslashreplace' replaces the character or byte, which cannot be encoded or decoded, with the hexadecimal format \xhh, \uxxxx or \Uxxxxxxxx for encoding or \xhh for decoding.
    • You can see more error handlers.
    • You can create your own error handler with codecs.register_error().

<Create a string>: 

v = str() # Empty str v = str(object='') # Empty str v = str(object='12') # str v = str(object=b'12') # bytes v = str(object=bytearray(b'12')) # bytearray v = str(object=12) # int v = str(object=1.2) # float v = str(object=1.2+3.4j) # complex v = str(object=True) # bool v = str(object=[1, 2, 3]) # list v = str(object=(1, 2, 3)) # tuple v = str(object={1, 2, 3}) # set v = str(object=frozenset({1, 2, 3})) # frozenset v = str(object={'name':'John'}) # dict v = str(object={'name':'John'}.keys()) # dict.keys() v = str(object={'name':'John'}.values()) # dict.values() v = str(object={'name':'John'}.items()) # dict.items() v = str(object=iter([1, 2, 3])) # iterator v = str(object=range(1, 4) # range v = str(object=lambda: 10) # function # No errors
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# Empty str print(str()) print(str(object='')) # Nothing
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v = str(object='12') # str  print(v, v[0], v[1]) # 12 1 2
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v = str(object=b'12') # bytes  print(v, v[0], v[1], v[2], v[3], v[4]) # b'12' b ' 1 2 '
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v = str(object=bytearray(b'12')) # bytearray  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # bytearray(b'12') b y t e a r r a y (
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v = str(object=12) # int  print(v, v[0], v[1]) # 12 1 2
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v = str(object=1.2) # float  print(v, v[0], v[1], v[2]) # 1.2 1 . 2
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v = str(object=1.2+3.4j) # complex  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # (1.2+3.4j) ( 1 . 2 + 3 . 4 j )
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v = str(object=True) # bool  print(v, v[0], v[1], v[2], v[3]) # True T r u e
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v = str(object=[1, 2, 3]) # list  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8]) # [1, 2, 3] [ 1 , 2 , 3 ]
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v = str(object=(1, 2, 3)) # tuple  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8]) # (1, 2, 3) ( 1 , 2 , 3 )
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v = str(object={1, 2, 3}) # set  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8]) # {1, 2, 3} { 1 , 2 , 3 }
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v = str(object=frozenset({1, 2, 3})) # frozenset  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # frozenset({1, 2, 3}) f r o z e n s e t (
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v = str(object={'name':'John'}) # dict  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # {'name': 'John'} { ' n a m e ' : '
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v = str(object={'name':'John'}.keys()) # dict.keys()  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # dict_keys(['name']) d i c t _ k e y s (
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v = str(object={'name':'John'}.values()) # dict.values()  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # dict_values(['John']) d i c t _ v a l u e
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v = str(object={'name':'John'}.items()) # dict.items()  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # dict_items([('name', 'John')]) d i c t _ i t e m s
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v = str(object=iter([1, 2, 3])) # iterator  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # <list_iterator object at 0x00000200F4715930> < l i s t _ i t e r
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v = str(object=range(1, 4)) # range  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # range(1, 4) r a n g e ( 1 , 4
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v = str(object=lambda: 10) # function  print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]) # <function <lambda> at 0x00000200F3EA8E00> < f u n c t i o n
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<Decode a byte string to a string>: 

print(str(object=b'', encoding='utf-8', errors='strict')) print(str(encoding='utf-8', errors='strict')) print(str(encoding='utf-8')) print(str(errors='strict')) # Nothing
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='utf-8') print(b) # b"L\xd1\x91\xd1\x82's g\xcf\x86!"  print(str(object=b, encoding='utf-8')) # Lёт's gφ!
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='utf-7') print(b) # b"L+BFEEQg's g+A8Y!"  print(str(object=b, encoding='utf-7')) # Lёт's gφ!
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='utf-16') print(b) # b"\xff\xfeL\x00Q\x04B\x04'\x00s\x00 \x00g\x00\xc6\x03!\x00"  print(str(object=b, encoding='utf-16')) # Lёт's gφ!
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='big5') print(b) # b"L\xc7\xce\xc7\xdb's g\xa3p!"  print(str(object=b, encoding='big5')) # Lёт's gφ! (Let's go!)
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='ascii', errors='ignore') print(b) # b"L's g!"  print(str(object=b, encoding='ascii', errors='ignore')) # L's g!
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='ascii', errors='replace') print(b) # b"L??'s g?!"  print(str(object=b, encoding='ascii', errors='replace')) # L??'s g?!
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='ascii', errors='xmlcharrefreplace') print(b) # b"L&#1105;&#1090;'s g&#966;!"  print(str(object=b, encoding='ascii', errors='xmlcharrefreplace')) # L&#1105;&#1090;'s g&#966;!
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='ascii', errors='backslashreplace') print(b) # b"L\\u0451\\u0442's g\\u03c6!"  print(str(object=b, encoding='ascii', errors='backslashreplace')) # L\u0451\u0442's g\u03c6!
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import codecs def hashreplace_handler(x): return ((x.end - x.start) * '#', x.end) codecs.register_error('hashreplace', hashreplace_handler) v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='ascii', errors='hashreplace') print(b) # b"L##'s g#!"  print(str(object=b, encoding='ascii', errors='hashreplace')) # L##'s g#!
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v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='ascii', errors='strict') # UnicodeEncodeError: 'ascii' codec can't encode characters # in position 1-2: ordinal not in range(128)
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import codecs def hashreplace_handler(x): return ((x.end - x.start) * '#', x.end) codecs.register_error('hashreplace', hashreplace_handler) v = "Lёт's gφ!" # Let's go!  b = v.encode(encoding='utf-8', errors='strict') print(b) # b"L\xd1\x91\xd1\x82's g\xcf\x86!"  print(str(object=b, encoding='ascii', errors='ignore')) # L's g!  print(str(object=b, encoding='ascii', errors='replace')) # L����'s g��!  print(str(object=b, encoding='ascii', errors='backslashreplace')) # L\xd1\x91\xd1\x82's g\xcf\x86!  print(str(object=b, encoding='ascii', errors='hashreplace')) # L####'s g##!  print(str(object=b, encoding='ascii', errors='strict')) # UnicodeDecodeError: 'ascii' codec can't decode byte 0xd1 # in position 1: ordinal not in range(128)  print(str(object=b, encoding='ascii', errors='xmlcharrefreplace')) # TypeError: don't know how to handle UnicodeDecodeError in error callback
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