Type Casting in Python

What is Type Casting? Type casting means converting one data type to another. For example, converting a number to a string or a string to a number. Python provides built-in functions to do this.

Why Use Type Casting?

Sometimes, you need to change the type of a value to perform certain operations. For example:

• Joining text and numbers: You cannot directly combine a number with text, so you need to convert the number to a string.
• Mathematical operations: If a number is stored as a string, you must convert it to an integer or float to perform calculations.

Common Type Casting Functions

Here are the most commonly used type casting functions in Python:

• int(): Converts a value to an integer.
• float(): Converts a value to a floating-point number (decimal).
• str(): Converts a value to a string.

Examples of Type Casting

Let's look at some examples to understand how type casting works:

1. Converting Numbers to Strings

When you want to combine a number with text, you need to convert the number to a string first:

# Example 1: Number to String
age = 25
# Convert age to a string and combine it with text
message = "I am " + str(age) + " years old."
print(message)
      

Output: I am 25 years old.

2. Converting Strings to Numbers

When you need to perform calculations with user input, you can convert a string to a number:

# Example 2: String to Integer
user_input = "5"  # Input is always a string
# Convert the string to an integer
number = int(user_input)
# Perform a calculation
result = number * 2
print("The result is:", result)
      

Output: The result is: 10

3. Converting Integers to Floats

If you want more precise calculations, you can convert integers to floating-point numbers:

# Example 3: Integer to Float
number = 10
# Convert the integer to a float
float_number = float(number)
print("The float value is:", float_number)
      

Output: The float value is: 10.0

Important Note

You cannot directly add a string and an integer. It will cause an error. Example:

# This will cause an error
age = 25
message = "I am " + age + " years old."
print(message)
      

Error: TypeError: can only concatenate str (not "int") to str

To fix this, convert age to a string using str(age).

Practice Example

Here’s a small program to practice type casting:

# Practice: Combine user input with type casting
name = input("Enter your name: ")
age = input("Enter your age: ")  # Input is a string
# Convert age to an integer
age_next_year = int(age) + 1
# Display the message
print("Hello, " + name + "! Next year, you will be " + str(age_next_year) + " years old.")
      

Example Output:

Enter your name: John

Enter your age: 25

Hello, John! Next year, you will be 26 years old.