Type Conversion

Type conversion means changing a value from one data type to another. Python provides built-in functions that make it easy to convert values between different data types.

What is Type Conversion?

Python variables can contain values of different data types. Sometimes a program needs a value in a different type to perform a particular operation.

For example, input received using input() is stored as a string. If we want to perform mathematical calculations, we can convert that string into an integer or float.

Common Type Conversion Functions

1. Convert to Integer using int()

The int() function converts a compatible value into an integer.

age = "25"

age = int(age)

print(age)
print(type(age))

Output

25
<class 'int'>

2. Convert to Float using float()

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

price = "499.50"

price = float(price)

print(price)
print(type(price))

Output

499.5
<class 'float'>

3. Convert to String using str()

The str() function converts a value into a string.

age = 25

age_text = str(age)

print(age_text)
print(type(age_text))

Output

25
<class 'str'>

4. Convert to Boolean using bool()

The bool() function converts a value to either True or False.

value = 1

result = bool(value)

print(result)
print(type(result))

Output

True
<class 'bool'>

Type Conversion with input()

The input() function returns user input as a string. Therefore, numerical input usually needs to be converted before performing calculations.

age = input("Enter your age: ")

age = int(age)

print("Your age is:", age)

Example Input

Enter your age: 25

Output

Your age is: 25

Type Conversion for Calculations

Consider a simple student marks example. The marks are received from the user as strings, so we convert them into integers before calculating the total.

math = int(input("Enter Math marks: "))
python = int(input("Enter Python marks: "))

total = math + python

print("Total Marks:", total)

Example

Enter Math marks: 80
Enter Python marks: 90

Total Marks: 170

Convert String to List

The list() function can convert an iterable such as a string into a list of individual elements.

text = "SAM"

letters = list(text)

print(letters)

Output

['S', 'A', 'M']

Convert List to Tuple

The tuple() function can convert a list into a tuple.

courses = ["Python", "C#", "Java"]

course_tuple = tuple(courses)

print(course_tuple)
print(type(course_tuple))

Output

('Python', 'C#', 'Java')
<class 'tuple'>

Convert List to Set

The set() function can be used to create a set and remove duplicate values.

numbers = [10, 20, 20, 30, 30]

unique_numbers = set(numbers)

print(unique_numbers)

Output:

{10, 20, 30}

Implicit Type Conversion

Sometimes Python automatically converts one compatible numeric type into another during an operation.

For example, when an integer and a float are added, Python produces a float result.

number1 = 10
number2 = 5.5

result = number1 + number2

print(result)
print(type(result))

Output

15.5
<class 'float'>

Explicit Type Conversion

When the programmer manually converts a value using functions such as int(), float(), or str(), it is called explicit type conversion.

number = "100"

number = int(number)

print(number + 50)

Output

150

Invalid Type Conversion

Not every value can be converted into every data type. For example, normal text cannot be directly converted into an integer.

value = "Python"

number = int(value)

This causes a ValueError because "Python" is not a valid integer.

number1 = int(input("Enter first number: "))
number2 = int(input("Enter second number: "))

sum = number1 + number2

print("Sum:", sum)

Enter first number: 10
Enter second number: 20
Sum: 30