Type Casting
In Python, you can explicitly set (force) a specific data type for a variable using type casting.
This is useful when working with user input, data conversion, calculations, or formatting output.
Python provides built-in functions to convert one data type into another.
What Is Type Casting?
Type casting means converting one data type into another using built-in functions.
Common casting functions:
int()float()str()bool()list()tuple()set()dict()
Definition
Type casting allows you to control the data type of a variable explicitly.
Setting Integer Type (int)
Used to convert values into integers.
python
x = int(10)
print(x)
python
y = int(9.8)
print(y)
python
z = int("100")
print(z)
Note
Strings must contain only numbers to convert to int.
Setting Float Type (float)
Used to convert values into floating-point numbers.
python
x = float(10)
print(x)
python
y = float("3.14")
print(y)
python
z = float(5)
print(z)
Setting String Type (str)
Used to convert values into strings.
python
x = str(10)
print(x)
python
y = str(3.14)
print(y)
python
z = str(True)
print(z)
Setting Boolean Type (bool)
The
bool() function converts values to True or False.python
print(bool(1))
python
print(bool(0))
python
print(bool(""))
python
print(bool("Python"))
Rule
0,None, empty string →False- Everything else →
True
Setting List Type (list)
Used to convert iterable objects into a list.
python
x = list((1, 2, 3))
print(x)
python
y = list("Python")
print(y)
python
z = list(range(5))
print(z)
Setting Tuple Type (tuple)
Used to convert iterable objects into a tuple.
python
x = tuple([1, 2, 3])
print(x)
python
y = tuple("Python")
print(y)
python
z = tuple(range(3))
print(z)
Setting Set Type (set)
Used to convert iterable objects into a set (unique values only).
python
x = set([1, 2, 2, 3])
print(x)
python
y = set("Python")
print(y)
python
z = set((10, 20, 20, 30))
print(z)
Setting Dictionary Type (dict)
Used to create dictionaries from key-value pairs.
python
x = dict(name="Python", version=3)
print(x)
python
y = dict([(1, "one"), (2, "two")])
print(y)
python
z = dict(zip(["a", "b"], [1, 2]))
print(z)
Setting Complex Type (complex)
Used to create complex numbers.
python
x = complex(3)
print(x)
python
y = complex(2, 5)
print(y)
python
z = complex("3+4j")
print(z)
Casting User Input (Very Important)
User input is always treated as a string.
python
age = int(input("Enter age: "))
print(age)
python
price = float(input("Enter price: "))
print(price)
python
name = str(input("Enter name: "))
print(name)
Common Casting Errors
Invalid Conversion
python
# int("Python") # Error
Safe Conversion Example
python
num = "10"
result = int(num)
print(result)
Caution
Always validate input before casting to avoid runtime errors.
Why Setting Data Types Is Important
Setting specific data types helps to:
- Avoid runtime errors
- Perform correct calculations
- Handle user input properly
- Write predictable and clean code
Key Takeaway
Type casting gives you full control over how data is stored and processed.
Summary
- Python automatically assigns data types
- Type casting sets a specific data type manually
- Use
int(),float(),str(),bool()commonly - Iterables can be converted to list, tuple, set
- User input always needs casting
Exercise
- Convert a string number into integer
- Convert an integer into float
- Convert a word into a list
- Check boolean value of empty and non-empty strings