Question

Write a C++ statement that uses the manipulator setfill to output a line containing 35 stars, as in the following line: ***********************************

Short answer

Use `std::cout << std::setfill('*') << std::setw(35) << "" << std::endl;`.

Step-by-step solution

Understand the Problem

The task requires writing a C++ statement that outputs a line consisting of 35 star ('*') characters, using the `setfill` manipulator to achieve this. The `setfill` manipulator is typically used in conjunction with output streams to specify the fill character for output padding.

Include Necessary Library

In C++, to use manipulator functions like `setfill`, you need to include the iostream and iomanip libraries. These libraries allow you to perform input and output operations. Add `#include ` and `#include ` at the beginning of your C++ code.

Set Up Output Stream

First, you need to ensure you use the proper output stream object, `std::cout`, as part of the output operation. This object allows you to print output to the console.

Apply `setfill` and `setw` Manipulators

Use `setw` to set the width of the output and `setfill` to specify the fill character. For this problem, you want a width of 35 and a fill character of '*'. The statement will look like this: ```cpp std::cout << std::setfill('*') << std::setw(35) << "" << std::endl; ```

Output the Line

The statement constructed in the previous step combines the manipulators with the output stream. By setting the width to 35 and filling with '*', it will output 35 stars to the console, which is the required result.

Key concepts

setfill manipulator

The `setfill` manipulator in C++ is used to specify a particular character that will fill the unused spaces in the output. It's particularly helpful when you want to align data with a specific width or format your output in a consistent way.
Imagine you have a situation where you want every line of text to be 10 characters long. You can use `setfill` to ensure that any space not used by actual content is filled with a specific character, such as '*'. This can be applied not just to lines of text, but also for visual alignment when displaying numbers.
To utilize `setfill`, you need to combine it with `setw`, which determines the width of the field. For instance:

• `std::cout << std::setfill('*') << std::setw(35) << "";` outputs 35 stars because, after setting the width with `setw`, `setfill('*')` fills the line with asterisks.

By understanding how to use `setfill`, you can enhance the presentation of your console output, making it appear more organized and professional.

iomanip library

The `iomanip` library in C++ is crucial when you're dealing with input and output formatting. It stands for input-output manipulation, and as the name suggests, it provides a collection of manipulators that allow you to control how data is displayed.
This library is incredibly handy for fine-tuning how numbers, strings, and other data types are presented on the screen.

• `setfill`, as we just detailed, fills character spaces.
• `setw` sets field width.
• Other manipulators like `setprecision` help control the number of decimal places displayed.

By including `#include `, you're enabling these advanced formatting capabilities, which are especially beneficial in creating user-friendly output for console applications or developing sophisticated reporting tools.

output stream

In C++, the output stream is your primary way of displaying data to the console. The object `std::cout` is the standard output stream provided by the language, and it's used to send your program's output to the terminal or command prompt.
Output streams are part of the standard library, under ``, allowing easy-to-read and write operations. When you use `std::cout`, you're typically sending text or numbers to be displayed.
Streams can also be manipulated using various I/O manipulators, such as `setfill` and `setw`, to control the appearance of your output. For example:

• `std::cout << "Hello, World!";` outputs "Hello, World!" to the console.
• `std::cout << std::setfill('-') << std::setw(10) << "Hi";` will append some dashes to make the field 10 characters wide.

Understanding streams is fundamental for efficiently handling data presentation in C++. They are integral to producing neat, concise, and organized console outputs.