Python Study Notes

By MoeunRithi Sreylompong

🔹 Variables

• Store data values in memory.

• Defined by: name, value, type, scope, mutability.

• Created with = operator.

• Python is dynamically typed → type inferred automatically.

• Common types:

• int → whole numbers

• float → decimals

• str → text

• bool → True/False

• list → [1,2,3] (mutable)

• tuple → (1,2,3) (immutable)

• dict → {"key":"value"}

• set → {1,2,3}

🔹 Basic Operations

• Arithmetic: + - * / // % **

• Assignment: = += -= *= /=

• Comparison: == != > < >= <=

• Logical: and or not

• Membership: in, not in

🔹 Strings

• Concatenation: "Hello" + "World" → "HelloWorld"

• f‑strings: f"My name is {name}"

• Length: len("Python") → 6

• Indexing & slicing:
  python
  text = "Python"

text[0]     # "P"

text[0:3]   # "Pyt"

text[::-1]  # "nohtyP"

• Methods:

• "hello".upper() → "HELLO"

• "HELLO".lower() → "hello"

• " hi ".strip() → "hi"

• "Java".replace("Java","Python") → "Python"

• Splitting: "This is a sentence".split() → ['This','is','a','sentence']