Question

Write some \(\mathrm{C}++\) code that will read a line of text and echo the line with all uppercase letters deleted.

Short answer

Question: Write a C++ program that reads a line of text and outputs the same line with all uppercase letters removed. Answer: You can create a C++ program that follows these steps: 1. Include the necessary headers and namespace. 2. Create a main function. 3. Read a line of text from the user. 4. Iterate through the characters and remove uppercase letters. 5. Display the modified string. Here's the complete code: ```cpp #include #include using namespace std; int main() { string text; cout << "Enter a line of text: "; getline(cin, text); string output; for(char letter : text) { if(!isupper(letter)) { output += letter; } } cout << "Output: " << output << endl; return 0; } ``` This program reads a line of text from the user, iterates through each character to remove uppercase letters, and then displays the modified string.

Step-by-step solution

Include the necessary headers and namespace

Firstly, we need to include "iostream" and "string" header files and the standard namespace std, as we will be using the cin, cout and getline functionalities: ```cpp #include #include using namespace std; ```

Create a main function

Next, we'll write the main function where we'll prompt the user for input and process the given text: ```cpp int main() { // Your code will be placed here } ```

Read a line of text from the user

Inside the main function, declare a string variable called "text" and use the getline() function to read a line of text from the user: ```cpp string text; cout << "Enter a line of text: "; getline(cin, text); ```

Iterate through the characters and remove uppercase letters

Now, we will iterate through each character in the given text and check if it is an uppercase letter. If it is not, we will add it to a new string called "output": ```cpp string output; for(char letter : text) { if(!isupper(letter)) { output += letter; } } ```

Display the modified string

Finally, we will display the resulting string without uppercase letters to the user: ```cpp cout << "Output: " << output << endl; ``` Now, let's combine all the steps into a complete C++ program: ```cpp #include #include using namespace std; int main() { string text; cout << "Enter a line of text: "; getline(cin, text); string output; for(char letter : text) { if(!isupper(letter)) { output += letter; } } cout << "Output: " << output << endl; return 0; } ``` This program will successfully read a line of text and output the line with all uppercase letters removed.

Key concepts

Basic Input/Output

In C++ programming, handling input and output is a fundamental skill that helps the programmer interact with the user. We use the iostream header to enable basic input/output operations.
To read a line of text from the user, we use the `cin` object along with the `getline()` function. This function allows us to capture an entire line of text until the user presses the Enter key.

• `cin` is used for reading standard input like numbers or single words.
• `getline(cin, text)` reads the whole line into a string called `text`, including spaces.

After capturing input, we may wish to display some information back to the user. For this, `cout` comes in handy. It helps us print text, numbers, and results to the console.
For example, `cout << "Output: " << output << endl;` displays a message followed by the variable `output` and ends the line with `endl` for proper formatting.

String Manipulation

String manipulation is a key area in C++ programming that allows us to alter and process strings according to our requirements. Using the `string` class, as included with the `string` header, we can easily work with text in a flexible manner.
In our program, we create a string variable `text` to store user input. We then iterate over it to perform operations like removing specific characters.

• To join or concatenate strings, we can use the `+` operator.
• We can access individual characters in a string using the `[]` operator or range-based for loops in C++11 and above.
• Using loops, we can navigate each character and apply conditions, such as checking if the character is uppercase and ignoring it if true.

These operations make string manipulation extremely versatile for altering or analyzing user input as needed.

Character Functions

C++ provides several built-in character functions to work with individual characters, particularly to determine attributes like whether a character is upper or lower case, a digit, etc. These utilities are provided through the `cctype` header, which is not explicitly mentioned in the exercise, but functions such as `isupper()` come from there by standard.
In the example, we used `isupper(letter)` to check if a character is uppercase. If the function returns true, we skip adding it to the output.

• `isupper(char)` function checks if the character is an uppercase letter, returning `true` or `false`.
• Functions like `tolower(char)` and `toupper(char)` help in converting characters to lower and uppercase, respectively.

By understanding and utilizing these character functions, we can make informed decisions about how to process and modify text data in C++.