Question

Write a program that reads a series of strings and prints only those strings that end with the letters "ED."

Short answer

Initialize input reading, filter strings with endswith('ED'), and print matching strings.

Step-by-step solution

Initialize the Program

Begin by setting up your program environment. If you're using Python, for example, open your Python IDE or terminal and start with the standard `if __name__ == "__main__":` structure to ensure your code runs as a script.

Input Reading Setup

Create a mechanism to read multiple strings from the user. You can use a simple `while` loop to keep reading strings until a certain condition is met, such as a specific termination word being entered (e.g., 'STOP'). Alternatively, you can prompt the user to enter a fixed number of strings.

Filter Strings

For each string read from the user, check if it ends with 'ED'. You can use Python's `str.endswith()` method which returns `True` if the string ends with the specified suffix and `False` otherwise. E.g., `if string.endswith('ED'):`.

Output the Result

If the check in Step 3 is `True`, print the string. Use a simple `print()` statement to display strings that end with 'ED' to the user.

Key concepts

String Manipulation

In programming, string manipulation is an essential skill, particularly in languages like C++. String manipulation involves modifying, parsing, or analyzing strings of text via code. In our exercise, we use string manipulation to check for a specific pattern, specifically whether a string ends with 'ED'.

To achieve this in a C++ program, you can use methods that access parts of the string:

• substr(): This function extracts a substring from a string. It's useful if you need to check specific segments of larger strings.
• compare(): This function is ideal for checking whether a substring matches a certain criterion, such as ending with 'ED'. You could extract the last two characters using substr() and then compare them.

Understanding these functions allows you to effectively manipulate and work with strings within your program.

Conditional Statements

Conditional statements, like if statements, are decision-making structures in programming. They allow your program to execute different actions based on certain conditions. In our task of checking if strings end with 'ED', conditional statements play a crucial role.

In C++, the syntax for conditional statements generally involves using the if keyword followed by a condition in parentheses. If the condition evaluates to true, the code inside the curly braces runs. For our string-checking example, you might write:

• if (myString.ends_with("ED")): Using this C++20 feature, you can directly check if a string ends with another string. It's a clean and straightforward approach.
• Older C++ versions: Could use substr() along with == operator:
• if (myString.substr(myString.size() - 2) == "ED"): Extracts the last two characters and compares them to 'ED'.

Conditional statements, therefore, help you decide what should happen next in your code based on whether the strings meet the specified conditions.

Loops

Loops are fundamental to programming because they allow code to be executed repeatedly based on a predefined condition. In our task, we want to read multiple strings until a user-defined condition ends the loop.

In C++, you commonly use while loops or for loops. A while loop is particularly useful for this task when you don't know how many iterations are necessary in advance. Here's a simple example:

• while (getline(cin, myString) && myString != "STOP"): This keeps reading strings until the user inputs "STOP". This is a practical approach when you're unsure of the number of strings.

An alternative is a for loop, if you specifically know the number of strings to read from the user, such as reading a fixed number of strings:

• for (int i = 0; i < n; i++): If you know the exact number of iterations you need.

Understanding loops is essential for efficiently processing multiple strings and making decisions based on user input. Whether through for or while loops, they form the backbone for repeated task execution in programming.