Question

include using namespace std; int main() { int count; int alpha[5]; alpha[0] = 5; for (count = 1; count < 5; coun… # What is the output of the following program? #include using namespace std; int main() { int count; int alpha[5]; alpha[0] = 5; for (count = 1; count < 5; count++) { alpha[count] = 5 * count + 10; alpha[count - 1] = alpha[count] - 4; } cout << "List elements: "; for (count = 0; count < 5; count++) cout << alpha[count] << " "; cout << endl; return 0; }

Short answer

The output is: "List elements: 11 16 21 26 30"

Step-by-step solution

Initialize Variables and Array

The program begins with the declaration of an integer variable `count` and an array `alpha` of size 5. The first element of the array `alpha[0]` is initialized to 5.

Process the First for Loop

A `for` loop runs from `count = 1` to `count < 5`. Inside this loop, two operations occur: 1. `alpha[count]` is assigned the value `5 * count + 10`. 2. `alpha[count - 1]` is modified to be `alpha[count] - 4`.

Calculating Values in the First Loop

Iterate through the first loop to update the array: - When `count=1`: - `alpha[1] = 5 * 1 + 10 = 15` - `alpha[0] = 15 - 4 = 11` - When `count=2`: - `alpha[2] = 5 * 2 + 10 = 20` - `alpha[1] = 20 - 4 = 16` - When `count=3`: - `alpha[3] = 5 * 3 + 10 = 25` - `alpha[2] = 25 - 4 = 21` - When `count=4`: - `alpha[4] = 5 * 4 + 10 = 30` - `alpha[3] = 30 - 4 = 26`

Output the List Elements

A second `for` loop iterates from `count = 0` to `count < 5`, printing each element of the `alpha` array. The expected output elements are: `11 16 21 26 30`.

Key concepts

for loop

In C++, a `for loop` is a powerful control structure that allows you to repeat a block of code a specific number of times. They consist of three main parts separated by semicolons: initialization, condition, and increment.
In the context of our program, the first `for loop` is used to update the values of the `alpha` array starting from the index 1 to 4. Here’s how it’s structured:

• Initialization: `count` is initially set to 1.
• Condition: As long as `count` is less than 5, the loop will continue.
• Increment: After each iteration, `count` is increased by 1.

This loop efficiently calculates values and updates elements in the array `alpha`.
The second `for loop` is simpler. It runs from 0 to 4, printing each element of the `alpha` array. Each iteration of the loop accesses and outputs the value at the current index, helping generate the final sequence of numbers.

array manipulation

Arrays are a fundamental part of C++ programming, providing a way to store multiple values in a single variable. They help manage related data using a single name and index numbers.
In this program, an integer array `alpha` of size 5 is declared. The challenge is to manipulate this array within a `for loop`, assigning and modifying its elements based on specific conditions.
The critical operations performed on the array include:

• Initialization: Setting `alpha[0]` to 5 before starting the `for loop`.
• Updating: For each loop iteration, `alpha[count]` is calculated and assigned using the formula `5 * count + 10`. Immediately after, the value at `alpha[count - 1]` is recalculated as `alpha[count] - 4`.

Notice how these repeated operations allow each element to be systematically adjusted, ensuring a smooth and predictable variety of values in the array. Through efficient manipulation, we can prepare the array for final output.

program output

Understanding the output of a C++ program involves tracing the results of calculated and printed values. In the provided example, after the array `alpha` undergoes updates within the `for loop`, the program prints the list of elements.
This output process relies heavily on the second `for loop`, running through the entire array from the first element to the last. Here's what happens:

• Each element of `alpha` is printed in order, resulting in the sequence `11 16 21 26 30` being displayed on the console.
• The `cout` statement outputs each element, with a space in between for readability.
• Finally, the `endl` command ensures the output completes with a newline, making it clear and legible.

Thus, the program's output is the culmination of precise calculations carried out in loops and correctly formatted text display, transforming the numeric logic into a user-friendly result.