None and Binary Data
Real programs handle missing values and binary data. Use None to mark βno valueβ, and bytes/bytearray for raw binary content. Know when each is appropriate and how to convert safely between text and bytes.
None for βNo Valueβ
None is a single object meaning βnothing hereβ.
1234567result = None email = None print(result is None) # True print(email is None) # True if result is None: print("No result yet")
Use is None instead of truthiness checks, since 0 and "" are also falsey.
123value = 0 print(not value) # True print(value is None) # False
Defaults and Fallbacks
1234567x = None print(x or "unknown") # 'unknown' print("unknown" if x is None else x) x = 0 print(x or "unknown") # 'unknown' (maybe wrong) print("unknown" if x is None else x) # 0
Functions and Parameters
1234567def add_tag(text, tag=None): if tag is None: tag = "general" return f"[{tag}] {text}" print(add_tag("hello")) # [general] hello print(add_tag("hello", "news")) # [news] hello
bytes and bytearray for Binary Data
str holds text, bytes and bytearray hold raw byte values.
1234b1 = b"hello" b2 = bytes([72, 105]) buf = bytearray(b"abc") buf[0] = 65
Encoding and Decoding
UTF-8 is a text encoding that converts characters into bytes so they can be stored and transmitted, and it supports all Unicode characters while remaining compatible with ASCII.
123text = "cafΓ©" data = text.encode("utf-8") back = data.decode("utf-8")
Mixing Text and Bytes
123456try: b"ID:" + "123" except TypeError as e: print(e) ok = b"ID:" + "123".encode("utf-8")
Length Differences
123ch = "Γ©" len(ch) # 1 len(ch.encode()) # 2
Files
# with open("example.png", "rb") as f:
# blob = f.read()
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Real programs handle missing values and binary data. Use None to mark βno valueβ, and bytes/bytearray for raw binary content. Know when each is appropriate and how to convert safely between text and bytes.
None for βNo Valueβ
None is a single object meaning βnothing hereβ.
1234567result = None email = None print(result is None) # True print(email is None) # True if result is None: print("No result yet")
Use is None instead of truthiness checks, since 0 and "" are also falsey.
123value = 0 print(not value) # True print(value is None) # False
Defaults and Fallbacks
1234567x = None print(x or "unknown") # 'unknown' print("unknown" if x is None else x) x = 0 print(x or "unknown") # 'unknown' (maybe wrong) print("unknown" if x is None else x) # 0
Functions and Parameters
1234567def add_tag(text, tag=None): if tag is None: tag = "general" return f"[{tag}] {text}" print(add_tag("hello")) # [general] hello print(add_tag("hello", "news")) # [news] hello
bytes and bytearray for Binary Data
str holds text, bytes and bytearray hold raw byte values.
1234b1 = b"hello" b2 = bytes([72, 105]) buf = bytearray(b"abc") buf[0] = 65
Encoding and Decoding
UTF-8 is a text encoding that converts characters into bytes so they can be stored and transmitted, and it supports all Unicode characters while remaining compatible with ASCII.
123text = "cafΓ©" data = text.encode("utf-8") back = data.decode("utf-8")
Mixing Text and Bytes
123456try: b"ID:" + "123" except TypeError as e: print(e) ok = b"ID:" + "123".encode("utf-8")
Length Differences
123ch = "Γ©" len(ch) # 1 len(ch.encode()) # 2
Files
# with open("example.png", "rb") as f:
# blob = f.read()
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