Casting in Python refers to converting a variable from one data type to another. Unlike some languages, Python does this using built-in functions. This is useful when you need to convert data for calculations, comparisons, or formatting.

Why Casting is Important

When working with different data types, you may need to:

• Convert strings to numbers for calculations
• Format floats as strings for output
• Change integers to floats for division

 Basic Casting Functions

Python provides several built-in functions for type conversion:

1. Converting to Integer: int()

x = int(3.7)       # x = 3
y = int("10")      # y = 10

❗ int("abc") will raise a ValueError because "abc" cannot be converted to a number.

2. Converting to Float: float()

x = float(5)        # x = 5.0
y = float("3.14")   # y = 3.14

3. Converting to String: str()

x = str(100)       # x = "100"
y = str(3.14)      # y = "3.14"

4. Converting to Boolean: bool()

bool(0)        # False
bool(1)        # True
bool("")       # False
bool("Hello")  # True

 Rule of Thumb: 0, None, "", [], {}, and () are considered False; everything else is True.

 Example in Action

a = "10"
b = "5.5"

# Convert to proper types
a = int(a)
b = float(b)

# Perform operation
result = a + b
print(result)   # 15.5

Things to Watch Out For

1. Not all strings can be converted to numbers:

int("abc")  # ValueError

 2. Casting a float to int truncates (doesn't round):

int(3.99)  # 3

Test Yourself

Try to guess the output before running:

print(int("5") + float("2.3"))
print(str(10) + str(20))
print(bool("False"))

Summary

• Use int(), float(), str(), and bool() for conversions.
• Always validate input if it's coming from a user or external source.
• Remember type conversion can cause data loss (like float to int).