Question

What is the output of the following C++ code? double salary[5] = {25000, 36500, 85000, 62500, 97000}; double raise = 0.03; cout << fixed << showpoint << setprecision(2); for (int i = 0; i < 5; i++) cout << (i + 1) << " " << salary[i] << " " << salary[i] * raise << endl;

Short answer

The code outputs a sequence of lines showing each salary with a 3% raise.

Step-by-step solution

Initialize the Variables

The code initializes an array named `salary` with five elements: 25000, 36500, 85000, 62500, and 97000. A double variable `raise` is also initialized with the value 0.03, representing a 3% raise.

Setup Output Format

The `cout` statement is formatted to show output in fixed-point notation with two decimal places using `fixed`, `showpoint`, and `setprecision(2)`. This ensures all numbers have exactly two digits after the decimal point.

Loop Through the Array

A `for` loop iterates over the entire `salary` array. This loop starts with `i` equal to 0 and runs until `i` is less than 5, incrementing `i` by 1 in each iteration.

Display Each Employee's Details

Inside the loop, the `cout` statement outputs several pieces of information: - The index plus one, as an ordinal number (1, 2, 3, 4, 5) - The original salary at the current index in the array `salary[i]` - The computed raise, which is calculated as `salary[i] * raise`. Each component is separated by a space, and values will adhere to the fixed-point formatting set earlier.

Key concepts

C++ loops

Loops in C++ are essential for automating repetitive tasks. They allow you to execute a block of code multiple times without having to manually repeat the statements. In the given exercise, a `for` loop is used to iterate over an array of salaries.

Here's how loops work:

• The `for` loop has three main parts within its parentheses:
• Initialization: `int i = 0;` sets up the loop control variable, in this case, `i` starts at 0.
• Condition: `i < 5;` determines how long the loop will repeat. This loop continues as long as `i` is less than 5.
• Increment: `i++` increases `i` by 1 after each loop iteration.
• The control variable `i` is used as an index to access array elements.
• Inside the loop, the current element and its calculated raise are output using `cout`.

Understanding loops is crucial because they make handling multiple data points easier and more efficient. Once you define how often you need to repeat a task, loops do the heavy lifting, allowing your code to remain clean and effective.

output formatting in C++

Output formatting is a feature in C++ that controls how data is displayed. It is particularly useful for presenting numerical results in a readable and professional manner.

In the exercise, `cout` is used with specific formatting functions:

• `fixed`: This manipulator forces the output to be in fixed-point notation, which is useful for displaying floating-point numbers in a customary format.
• `showpoint`: Ensures that the decimal point and trailing zeros are displayed, even if the number is a whole number, highlighting precision.
• `setprecision(2)`: This function specifies that the numbers should have two digits after the decimal point, guaranteeing uniformity in the output's numeric values.

These tools are vital when output needs to be human-friendly, such as financial reports or statistical data. Proper formatting not only makes data easier to read but also more professional, ensuring that any presentation remains coherent and informative.

floating-point arithmetic in C++

Floating-point arithmetic in C++ allows for the handling of real numbers, including fractions and decimals. It is a fundamental concept for any calculations that require precision beyond integers, such as financial computations or scientific data processing.

In the original exercise, a `double` array stores salaries, and a `double` variable `raise` represents the percentage increase applied to each salary:

• `double` is a floating-point data type that provides about 15 digits of precision, suitable for calculations where truncations could lead to significant errors.
• The expression `salary[i] * raise` dynamically calculates the raise for each salary in the array by multiplying the current salary by the raise factor (0.03 in this case).

Working with floating-point numbers involves considerations such as rounding errors, which is why output formatting is often coupled with arithmetic operations to maintain output clarity. Using `double` counteracts potential inaccuracies that can accumulate through arithmetic operations, keeping results as precise as they need to be.