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Type Casting

In Python, casting is the process of converting a variable from one type to another. Python has built-in functions for converting between data types.

Specify a Variable Type​

Python is an object-oriented language, and variables are objects.
You can specify the data type using casting functions:

x = int(1)     # x will be 1
y = int(2.8)   # y will be 2
z = int("3")   # z will be 3

int() - Integer Casting​

Converts a value to an integer. Works with floats and numeric strings.

x = int(1)      # 1
y = int(2.8)    # 2
z = int("3")    # 3
# w = int("abc")  # Error

float() - Floating-Point Casting​

Converts a value to a float. Works with integers and numeric strings.

a = float(1)      # 1.0
b = float("2.5")  # 2.5
c = float(3.0)    # 3.0

str() - String Casting​

Converts numbers or other types into a string.

x = str("s1")   # 's1'
y = str(2)      # '2'
z = str(3.0)    # '3.0'

Invalid Casting​

Some values can't be casted directly:

int("hello")     # ValueError
float("abc")     # ValueError

Use try/except to handle safely:

value = "abc"
try:
    number = int(value)
except ValueError:
    print("Invalid conversion")

Summary Table​

FunctionConverts toExample InputOutput
int()Integer"3"3
float()Float"3.5"3.5
str()String3.5"3.5"

Quick Notes​

  • Use casting to convert types manually.
  • Useful when handling user input, math, or data from files.
  • Always validate input before casting to avoid errors.