Question

Write a function def countwords(string) that returns a count of all words in the string string. Words are separated by spaces. For example, countionds ("yary had a 1ittle lasb") should retum 5.

Short answer

The function splits the string by spaces and counts the resulting words.

Step-by-step solution

Function Definition

Start by defining a function called `countwords` that takes one parameter `string`. This will serve as the input string that we want to analyze.

Split the String

Use the built-in `split()` method on the string. This method will break the string into a list of words using spaces as the delimiter. Example: `'mary had a little lamb'.split()` will return `['mary', 'had', 'a', 'little', 'lamb']`.

Count the Words

Once we have a list of words resulting from the split, use the `len()` function to count how many elements (words) are in the list. This will give us the total number of words in the string.

Return the Count

Return this word count as the output of the function. This will complete our implementation, providing the number of words found in the original string.

Key concepts

Python functions

In Python, functions are pivotal for creating reusable pieces of code. When you define a function, you set aside a block of code that can be executed later, whenever you need it. To start defining a function in Python, you use the `def` keyword, followed by the function's name and parentheses that may contain parameters.
For example:

• `def countwords(string):`

In this statement, `def` signifies that we're defining a function called `countwords`, with `string` as the argument or parameter that the function will use. The code within the function should be consistently indented.

• Functions can accept multiple parameters or might not require any parameters at all.
• They often include a return statement to send back a result or output.

Using functions helps keep your code organized, makes it easier to debug, and enhances code readability. It's a cornerstone for efficient Python programming.

String splitting

String splitting is essential for breaking down a string into manageable parts based on a specified separator or delimiter. In Python, the most common way to split a string is by using the `split()` method. By default, `split()` uses spaces as the delimiter and creates a list of substrings.

• For instance, `'hello world'.split()` will yield `['hello', 'world']`.

This method is versatile and can be adapted for different use cases:

• You can specify a different delimiter by passing it as an argument to `split()`, such as `split(',')` for splitting by commas.
• If you provide no argument, all whitespace in the string will act as the delimiter, including spaces, tabs, and new lines.
• An empty string as an argument will not split the string but can be useful in specific edge cases.

Understanding how to effectively manipulate and split strings allows programmers to process text efficiently and as needed for various applications.

Counting elements in Python

Counting elements in Python is a frequent task that you often perform when working with collections like lists, tuples, or strings. A fundamental tool you use for this task is the `len()` function. This built-in function calculates how many elements are present in a given item, often referred to as checking its length. Consider using `len()` on a list:

• For the list `['apple', 'banana', 'cherry']`, `len()` will return `3` because there are three items in the list.

When you split a string into a list of words, using `len()` on that list will immediately give you the number of words.

• This method is quick and requires just one line of code to perform a count after a `.split()` operation, as seen in `len('python code'.split())` which results in `2`.
• Manipulating and counting elements in this manner allows for efficient handling of data structures in Python programming.

By incorporating the `len()` function, you can evaluate the size or count of elements in any enumerable collection effortlessly.