Question

Write a program that inputs a sentence and counts the number of palindromes in it. A palindrome is a word that reads the same backward and forward. For example, "TRee" is not a palindrome, but "noon" is.

Short answer

Count the words that are palindromes in the input sentence by comparing each word with its reverse.

Step-by-step solution

Understand the Problem

We need to write a program that reads a sentence from the user and then counts how many words in that sentence are palindromes. A palindrome is a word that remains the same when its letters are reversed.

Read the Input

Use a function to read a sentence from the user. This can typically be done using a function like `input()` in Python, which captures user input as a string.

Split the Sentence into Words

Use a method like `split()` in Python to separate the input sentence into individual words, storing them in a list. This will allow us to iterate over each word to check if it is a palindrome.

Define a Function to Check Palindromes

Create a function that checks if a given word is a palindrome. This can be done by comparing the word to its reverse, which can be obtained using slicing, e.g., `word[::-1]`.

Iterate Through Words and Count Palindromes

Initialize a counter at zero. Loop through each word in the list, use the palindrome-checking function to decide if the word is a palindrome, and increase the counter accordingly.

Return the Count of Palindromes

Once the loop is completed, return or print the value of the counter, which represents the total number of palindromes in the input sentence.

Key concepts

String Manipulation

String manipulation involves modifying and preprocessing text to make it useful for specific tasks. In the context of palindrome detection, the first task is to split a sentence into words. In Python, this can be done using the `split()` method, which breaks a string based on spaces by default.
This gives a list of words to examine. Another crucial aspect of string manipulation is checking if a word is a palindrome. You can compare a string to its reverse by using slicing. For a word `word`, `word[::-1]` generates the string reversed.
If a word matches its reversed version, it is identified as a palindrome. Removing these language subtleties helps focus on logic, ensuring you spot palindromes accurately.

Function Definition

Defining functions allows us to encapsulate logic in reusable, well-structured units. In the exercise, we create a function to check if a word is a palindrome. This function will take a word as an argument and return `True` if it is a palindrome, otherwise `False`. Here's a simple example of such a function in Python:

• Define the function header using `def` followed by a name, such as `is_palindrome`.
• Include a parameter, like `word`.
• Within the function, compare the word with its reverse using slicing.
• Return a boolean value that represents if the word is a palindrome.

Function definition here helps modularize code and makes it easy to handle palindrome checks without rewriting the logic.

Iteration and Looping

Iteration and looping are fundamental programming concepts used to perform repetitive tasks.
In our palindrome detection exercise, looping allows us to examine each word from a list of words from the sentence. Using a `for` loop, iterate over each word in the list. For each word, call the palindrome checking function.
If the function returns `True`, it indicates the word is a palindrome, and we increment a counter that keeps track of the number of palindromes found. This loop runs until all words have been processed. The final value of the counter gives the total number of palindromes present in the input sentence. Iteration and looping make efficient program execution possible, especially when dealing with multiple elements in a collection.

User Input Handling

User input handling is about obtaining and managing the data users provide to the program. In our exercise, we're tasked with reading a sentence input by the user. In many programming languages, such as Python, this is achieved using the `input()` function. This function captures everything typed by the user and stores it in a variable as a string.
It's important to handle the input carefully, considering that user input can often be unpredictable. Once the sentence is captured, we perform operations on this string, like splitting it into words and examining each for palindromes.
By effectively handling input, we ensure our programs are robust, user-friendly, and ready to process data accurately.