In Python, a list is a way to store multiple items in a single variable. For example, you might have a list of numbers, names, or even a mix of different types of data. Sometimes, you need to know how many items are in a list. This is called the length of the list.
Python makes it very easy to find the length using a built-in function called len(). Let’s go through this step by step.
Step 1: What is a List?
A list is a collection of items written inside square brackets []. Items are separated by commas.
numbers = [5, 10, 15, 20]
This list has 4 items: 5, 10, 15, and 20.
Step 2: Why Do We Need the Length of a List?
Knowing the length of a list is useful when:
- You want to loop through all items.
- You want to check if the list is empty.
- You want to divide the list into parts.
- You want to display the number of items to the user.
Step 3: Using the len() Function
Python provides a simple function called len() to count the number of items in a list.
Syntax:
print(len(numbers))
Step 4: Storing the Length in a Variable
You can also store the result of len() in a variable if you want to use it later in your program.
Example:
fruits = [“apple”, “banana”, “cherry”]
count = len(fruits)
print(“There are”, count, “fruits in the list.”)
Output:
There are 3 fruits in the list.
Step 5: len() Works with Other Data Types Too
The len() Function is not just for lists. It also works with:
- Strings – counts the number of characters
- Tuples – count the number of items
- Dictionaries – count the number of key-value pairs
Example:
len(“hello”) # Output: 5
len((1, 2, 3)) # Output: 3
len({“a”: 1, “b”: 2}) # Output: 2
Conclusion
This article introduced various methods to determine the length of a list in Python.
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