Question
Answer and Explanation
The TypeError: 'int' object is not subscriptable occurs in Python when you attempt to use square bracket notation ([]) to access an element of an integer as if it were a list, tuple, or string. Integers, by definition, are singular numeric values and do not support item-based access.
Here's a breakdown of why this error happens and how to fix it:
Understanding Subscriptable Objects
Subscriptable objects in Python are data structures that allow accessing elements by their index or key using square brackets. Common examples include:
- Lists: my_list = [1, 2, 3]; print(my_list[0])
- Tuples: my_tuple = (4, 5, 6); print(my_tuple[1])
- Strings: my_string = "Hello"; print(my_string[2])
Integers are not sequences or collections; they represent single numeric values, therefore they are not subscriptable.
Common Causes of the Error
1. Incorrect Data Type: You may have unintentionally assumed a variable holds a list or similar, when it actually stores an integer. This often happens when a function returns an integer instead of a list, or when dealing with user inputs.
Example:
def get_value():
return 10
my_value = get_value()
print(my_value[0]) # This will raise the TypeError
2. Looping with Incorrect Index: When looping, especially with ranges, you could be trying to access an element of an integer thinking it is a range itself.
Example:
my_number = 5
for i in my_number:
print(i) # This will cause the TypeError
3. Function Return Issues: If a function should return a list or other subscriptable object, but due to logic errors actually returns an integer, it will cause this error.
How to Resolve the Error
1. Verify Data Types: Use the type() function to check the actual data type of your variable. Then handle the data according to its type and purpose.
Example:
def get_data():
# Intended return of a list, but the function has a bug
return 10
my_data = get_data()
if isinstance(my_data, list):
print(my_data[0])
else:
print("Data is not a list. Type is:",type(my_data))
2. Use Iterables Correctly: When iterating use the correct functions, for example: range() when you are trying to produce a sequence for looping, or directly iterate over a list if your variable is a list.
Example:
my_number = 5
for i in range(my_number):
print(i) # Correct usage, this would work fine
3. Debug Function Logic: Verify the logic inside your function, and check its return statements.
In summary, the TypeError: 'int' object is not subscriptable error is a reminder that Python strictly enforces data types. By verifying the type of your variables and using appropriate data structures, you can avoid this common error and write more robust code.