Question

One interesting application of computers is to display graphs and bar charts. Write an application that reads five numbers between 1 and 30. For each number that is read, your program should display the same number of adjacent asterisks. For example, if your program reads the number 7, it should display *******.

Short answer

Read input numbers, validate them, and print corresponding asterisk strings.

Step-by-step solution

Read the Input

First, prompt the user to input five numbers. Ensure that these numbers are between 1 and 30, inclusive. This can be done by using a programming language to collect inputs and validate them.

Validate the Input

Check each of the five numbers to make sure they are within the accepted range of 1 to 30. If a number falls outside this range, prompt the user to enter a valid number.

Initialize the Loop

Set up a loop to iterate over the list of five numbers. This loop will be used to process each number sequentially.

Generate the Asterisks

Within the loop, for each number read, generate a string consisting of the same number of asterisks. This can be done using string multiplication in most programming languages, e.g., `'*' * number` in Python.

Display the Results

As you generate the asterisk strings, print each one on a new line. Ensure the output is clear and matches the expected number of asterisks for each input number.

Key concepts

Input Validation

Input validation is crucial in ensuring that the program receives valid and expected data before proceeding with further operations. In Java programming, input validation helps in avoiding errors and potential crashes by checking the data received from the user.
To perform input validation for this exercise:

• Use a loop structure to repeatedly prompt the user for input until a valid number is received.
• Ensure that each inputted number is within the specified range of 1 to 30.
• If a number is outside this range, inform the user and ask them to re-enter the number.

This method not only prevents invalid data from being processed but also enhances the user experience by guiding them to the correct input format.

Loop Structures

Loop structures are fundamental in programming for executing code repeatedly based on conditions defined initially. In this context, loops manage the iteration over the list of five numbers to perform operations on each number sequentially. Java offers several loop types, such as `for`, `while`, and `do-while` loops, adaptable based on the purpose.
For this exercise:

• Use a `for` loop to iterate over the list of numbers efficiently.
• This loop will help in applying operations like validation, and later displaying the number as a series of asterisks.
• The loop ensures that each number is handled in the same way, thus maintaining consistent performance and output.

Loops are pivotal in ensuring programs handle repetitive tasks without manual intervention, thus minimizing errors and saving time.

String Manipulation

String manipulation involves altering, parsing, and operating on text data to achieve the desired format or result. In the context of this exercise, string manipulation is used to generate a sequence of asterisks based on the validated input numbers.
To manipulate strings for the output:

• Utilize the technique of string repetition, where a character like `*` is multiplied by the number inputted.
• For example, in Java, use the `String` method through loops to concatenate or append characters efficiently.
• Converting numbers into visual representation through symbols like asterisks makes the application interactive and visually intuitive.

This string manipulation is not only effective for this exercise but is also a common technique in many real-world applications where text processing and formatting are required.

Console Output

Console output is the mechanism through which a program communicates results back to the user. It plays a crucial role in user interaction and understanding what a program has executed.
In Java programming, you display output to the console using `System.out.println()` or `System.out.print()` methods. For this exercise, the console output is needed to display the generated asterisk patterns:

• Each sequence of asterisks corresponds directly to the input number.
• Print each sequence on a new line to ensure clarity and readability.
• Using `System.out.println()` allows for automatic new line creation after each output, making it ideal for distinct, line-separated displays.

By leveraging the console output effectively, the program becomes not only functional but also engaging and clear in its delivery of results.