Type Conversion in Python

In Python, type conversion (also known as type casting) is the process of converting a value from one data type to another. This is a common necessity in programming. For instance, you might receive numerical data as strings from a user input form and need to convert them to int or float to perform mathematical calculations.

Python supports two main types of conversion:

1. Implicit Type Conversion: This happens automatically by the Python interpreter when it needs to prevent data loss in operations involving different data types. For example, when you add an int and a float, Python will automatically convert the int to a float to perform the addition.
2. Explicit Type Conversion: This is when you, the programmer, manually convert a variable’s type using built-in functions like int(), str(), float(), etc.

Implicit Type Conversion

Let’s see an example where Python handles the conversion for you.

The result is: 15.5
The type of the result is: <class 'float'>

Explicit Type Conversion

Most of the time, you will need to perform explicit conversions using Python’s built-in functions.

Converting to Integer: int()

The int() function converts a value to an integer.

num_float = 9.8
num_int = int(num_float)
print(num_int) # Output: 9

str_num = "123"
num_int = int(str_num)
print(num_int) # Output: 123
 
# This would cause a ValueError:
# int("hello") 

true_int = int(True)
false_int = int(False)
print(true_int)  # Output: 1
print(false_int) # Output: 0

Converting to Float: float()

The float() function converts a value to a floating-point number.

From int: 100.0
From string: 3.14
From boolean: 1.0

Converting to String: str()

The str() function can convert almost any data type into its string representation. This is extremely useful for creating output messages that combine text and numbers.

My name is Alice and I am 30 years old.
My name is Alice and I am 30 years old.

Converting to Other Collection Types

You can also convert between different collection types like lists, tuples, and sets.

my_tuple = (1, 2, 3)
my_list = list(my_tuple)
print(my_list) # Output: [1, 2, 3]
 
my_string = "abc"
char_list = list(my_string)
print(char_list) # Output: ['a', 'b', 'c']

my_list = [1, 2, 3]
my_tuple = tuple(my_list)
print(my_tuple) # Output: (1, 2, 3)

my_list = [1, 2, 2, 3, 1]
my_set = set(my_list)
print(my_set) # Output: {1, 2, 3}