CodingPhiles
📦 Python Fundamentals
Module 2 · Topic 3

Type Conversion & Type Checking

Convert between data types using built-in functions and understand when Python converts types implicitly vs when you must do it explicitly.

Theory

Type Conversion (Casting) in Python:

Implicit Conversion (Coercion):
Python automatically converts types in some arithmetic operations:

  • int + float → float: 5 + 2.0 = 7.0
  • int + complex → complex: 5 + 3j = (5+3j)
  • bool + int → int: True + 5 = 6

Explicit Conversion (Casting):
Use built-in constructor functions:

| Function | Purpose | Example |
|----------|---------|--------|
| int() | Convert to integer | int("42") → 42, int(3.9) → 3 |
| float() | Convert to float | float("3.14") → 3.14, float(5) → 5.0 |
| str() | Convert to string | str(42) → "42", str([1,2]) → "[1, 2]" |
| bool() | Convert to boolean | bool(0) → False, bool("") → False |
| list() | Convert to list | list("abc") → ["a","b","c"] |
| tuple() | Convert to tuple | tuple([1,2]) → (1, 2) |
| set() | Convert to set | set([1,1,2]) → {1, 2} |
| dict() | Convert to dict | dict([(a,1),(b,2)]) → {"a":1,"b":2} |

Truthy & Falsy Values:
These convert to False: 0, 0.0, "", [], (), {}, set(), None, False
Everything else is True.

Syntax
# Explicit conversion
int("42")       # String to int → 42
float("3.14")   # String to float → 3.14
str(100)        # Int to string → "100"
bool(0)         # Int to bool → False
list("hello")   # String to list → ["h","e","l","l","o"]