Data Type Conversion in Python

Sometimes, we need to convert data types in Python, and this can generally be achieved by simply using the data type's name as a function.

Python provides two types of data type conversion:

1. Implicit Type Conversion - Handled automatically

2. Explicit Type Conversion - Requires the use of conversion functions

Implicit Type Conversion

In implicit type conversion, Python automatically converts one data type to another without our intervention.

In the example below, we perform operations on two different data types, and the lower data type (integer) is converted to the higher data type (floating point) to prevent data loss.

Example

num_int = 123
num_flo = 1.23

num_new = num_int + num_flo

print("num_int data type:", type(num_int))
print("num_flo data type:", type(num_flo))

print("num_new value:", num_new)
print("num_new data type:", type(num_new))

Output:

num_int data type: <class 'int'>
num_flo data type: <class 'float'>
num_new value: 124.23
num_new data type: <class 'float'>

Code Explanation:

In this example, we add two different data types, num_int and num_flo, and store the result in num_new. We then check the data types of these variables.

In the output, we see that num_int is an integer, num_flo is a float, and the new variable num_new is also a float. This happens because Python automatically converts smaller data types to larger ones to avoid data loss.

Let's look at another example where an integer is added to a string:

Example

num_int = 123
num_str = "456"

print("num_int data type:", type(num_int))
print("num_str data type:", type(num_str))

print(num_int + num_str)

Output:

num_int data type: <class 'int'>
num_str data type: <class 'str'>
Traceback (most recent call last):
  File "/runoob-test/test.py", line 7, in <module>
    print(num_int + num_str)
TypeError: unsupported operand type(s) for +: 'int' and 'str'

As shown in the output, trying to perform arithmetic operations between an integer and a string causes a TypeError. Python cannot perform implicit conversion in this case.

However, Python provides a solution called explicit conversion for these scenarios.

Explicit Type Conversion

In explicit type conversion, users convert the data type of an object to the desired data type. We use predefined functions like int(), float(), and str() to perform explicit type conversion.

Converting to Integer: int()

Example

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

Converting to Float: float()

Example

x = float(1)     # x will be 1.0
y = float(2.8)   # y will be 2.8
z = float("3")   # z will be 3.0
w = float("4.2") # w will be 4.2

Converting to String: str()

Example

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

To perform arithmetic between integers and strings, you can use explicit conversion.

Example

num_int = 123
num_str = "456"

print("num_int data type:", type(num_int))
print("Before conversion, num_str data type:", type(num_str))

num_str = int(num_str)  # Explicitly converting to integer
print("After conversion, num_str data type:", type(num_str))

num_sum = num_int + num_str

print("The sum of num_int and num_str is:", num_sum)
print("The data type of sum is:", type(num_sum))

Output:

num_int data type: <class 'int'>
Before conversion, num_str data type: <class 'str'>
After conversion, num_str data type: <class 'int'>
The sum of num_int and num_str is: 579
The data type of sum is: <class 'int'>

Here are some built-in functions that can convert between data types. These functions return a new object representing the converted value.