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

Outputs: 1 25000.00 750.00, 2 36500.00 1095.00, 3 85000.00 2550.00, 4 62500.00 1875.00, 5 97000.00 2910.00.

Step-by-step solution

Understand the Code Setup

The code defines an array `salary` with 5 double values and a variable `raise` set to 0.03. It then prepares the output stream to show numbers with two decimal points by using `showpoint` and `setprecision(2)`. The `fixed` manipulator ensures that the output is in fixed-point notation.

Initialize the Loop

The `for` loop is set to iterate over the indices of the array `salary` (from 0 to 4, as there are 5 elements). Each iteration processes a corresponding salary value.

Calculate and Print in Each Iteration

For each index `i` in the loop (from 0 to 4), the code does the following: it prints the employee number (which is `i + 1`), the salary at `salary[i]`, and the raise amount calculated as `salary[i] * raise`. The output is formatted with two decimal places.

Compile the Output

Finally, all the calculated information is gathered. For each salary, the output shows its index (starting from 1), the salary amount, and the calculated raise, all formatted according to the settings.

Key concepts

C++ for loop

In C++, a `for` loop helps us perform repetitive tasks efficiently. It is used when we know the number of iterations beforehand.
The loop has three parts: an initialization (`int i = 0`), a condition (`i < 5`), and an increment/decrement statement (`i++`).
\[\text{for (initialization; condition; increment/decrement)}\]- **Initialization**: This is where the loop variable is initialized. When our loop begins, `i` is set to `0` because array indexing starts at zero.
- **Condition**: The loop will continue to iterate as long as this condition is true. In our example, the loop continues as long as `i < 5`, which means it will execute five times.
- **Increment/Decrement**: Here, the value of `i` is increased by `1` after each iteration, preparing it for the next loop cycle.
Inside the loop, we access each element of the `salary` array by using `salary[i]`. In each iteration, it prints out the current employee number, their salary, and the calculated raise. This is a practical way to manage operations over an array in C++. Each iteration makes handling large datasets efficient and systematic, significantly reducing both errors and coding workload.

C++ output formatting

Formatting output in C++ is crucial for readability, especially when dealing with numerical data. C++ offers various manipulators to help format the output in a user-friendly way.
- **`fixed`**: This manipulator is used to display floating-point numbers in fixed-point notation, which makes the decimal point appear at a specific position.
- **`showpoint`**: Forces the output to show the decimal point, even for whole numbers, ensuring clarity.
- **`setprecision`**: This is particularly important when we want to specify the number of digits after the decimal point. In our program, `setprecision(2)` is used, which means numbers will be displayed with two decimal places.
Example: When dealing with the salary raises in the loop, these manipulators ensure that the calculated raise values are presented in a way that is consistent and easy to interpret.
If we print `3.00` instead of `3`, it maintains precision and avoids confusion, especially when presenting financial data. Using these tools helps to maintain uniformity across different outputs, making the results both professional and comprehensible.

C++ variables

Variables in C++ are fundamental as they store and manipulate data needed for program execution. Let's break down the types used in our example:
- **`double`**: This type is used for variables that need to store decimal numbers. It offers double precision floating-point capability, allowing for a wide range of values with a lot of precision. In our code, the `salary` array and `raise` variable both use `double` to handle monetary calculations efficiently without losing decimal accuracy.
- **`int`**: Basic integer type for storing whole numbers, crucial for counting iterations in loops. Here, it's used for the loop index `i`. Variables like `salary` and `raise` are initialized with starting values: - **`salary`**: An array with five elements representing different salary amounts. By using arrays, we store related pieces of data under a single named reference, making it easy to process multiple data points. - **`raise`**: A simple variable holding a constant raise percentage of `0.03` (3%).
Properly declaring and initializing variables is important to ensure that a program functions correctly. Different types have specific uses, and choosing the right type can help manage memory more effectively and make the code more reliable. Understanding these concepts is key to writing efficient and comprehensible C++ programs.