Variables and types

Python variables are names bound to objects—no int x = 5 type declarations like Java. Types live on objects; names can rebind to different types at runtime, similar to JavaScript but with stricter rules (e.g., no implicit string+number concat).

Common built-in types

• int, float — numbers (arbitrary-precision ints)
• str — Unicode text, immutable
• bool — True or False (capitalized)
• None — absence of value, like null in JS

Assignment and type()

count = 10
ratio = 0.75
name = "Ada"
ok = True
print(type(count), type(name))

Use type() or isinstance() at runtime. Optional static type hints come later—compare with C# compile-time checks.

Important interview questions and answers

1. Q: Dynamic vs static typing?
   A: Python resolves types at runtime on objects; Java/C# enforce variable types at compile time.
2. Q: Mutable vs immutable scalars?
   A: int, float, str, tuple are immutable; list, dict, set are mutable.

Self-check

1. What does type(3.14) return?
2. Can a name rebind from int to str?

Pitfall: Names bind to objects—a = b for lists aliases the same list, unlike copying value types in C# structs.