Question

What is the output of the following program segment? double temp[5]; for (int i = 0; i < 5; i++) temp[i] = pow(i, 2.0) + 2; for (int i = 0; i < 5; i++) cout << temp[i] << " "; cout << endl; temp[0] = pow(temp[1], 3); temp[1] = temp[4] - temp[2]; temp[2] = temp[0] - 5; for (int i = 0; i < 5; i++) cout << temp[i] << " "; cout << endl;

Short answer

Initial output: `2 3 6 11 18`. Modified output: `27 12 22 11 18`. The final printed results are these two sequences.

Step-by-step solution

Initialize Array with Calculated Values

The program starts by initializing a double array `temp` with 5 elements. The `for` loop is used to calculate and store values in the `temp` array. - For `i = 0`, `temp[0] = pow(0, 2) + 2 = 2`. - For `i = 1`, `temp[1] = pow(1, 2) + 2 = 3`. - For `i = 2`, `temp[2] = pow(2, 2) + 2 = 6`. - For `i = 3`, `temp[3] = pow(3, 2) + 2 = 11`. - For `i = 4`, `temp[4] = pow(4, 2) + 2 = 18`.

Print Initial Array Values

The program enters a loop to print the initial values stored in the `temp` array. The values printed will be: `2 3 6 11 18`.

Perform Array Value Modifications

After printing, the program modifies the array `temp` with specific calculations: - `temp[0] = pow(temp[1], 3);` which modifies `temp[0]` to `pow(3, 3) = 27`. - `temp[1] = temp[4] - temp[2];` which modifies `temp[1]` to `18 - 6 = 12`. - `temp[2] = temp[0] - 5;` which modifies `temp[2]` to `27 - 5 = 22`.

Print Modified Array Values

The program enters another loop to print the modified values stored in the `temp` array after changes. The new values printed will be: `27 12 22 11 18`.

Key concepts

Using for loops in C++ Arrays

In C++, a `for` loop is a powerful way to iterate over arrays and perform repetitive tasks efficiently. With a for loop, you can go through each element in an array, one by one. This is exactly how the loop works in our exercise. The code "for (int i = 0; i < 5; i++)" sets up a loop that starts at `i = 0` and ends when `i` reaches 4, which totally makes five iterations. During each iteration of the loop, we can perform operations using `i` to access specific elements in the array via the indexing mechanism.

• The "int i = 0;" initializes `i` to 0, the starting point of our loop.
• The "i < 5;" is a check condition that keeps the loop running as long as `i` is less than 5.
• The "i++" increases `i` by 1 in each loop iteration, moving to the next element of the array.

By understanding how `for` loops work, you can easily navigate through arrays and manipulate their data.

Fundamentals of Array Initialization in C++

Array initialization is a key step when working with arrays in C++. It sets the starting values for each element in the array. In our program, we initialize the `temp` array to have 5 elements. Using the `for` loop, each element is calculated and assigned a value based on a formula.

For this exercise:

• Inside the first `for` loop, each index `temp[i]` is assigned the value of `pow(i, 2.0) + 2`.
• This means for `temp[0]`, the value is `2`, for `temp[1]`, the value is `3`, and so on, until `temp[4]` which is initialized to `18`.

By assigning values in this manner, the array is both declared and filled with specific starting data all in one concise loop.

Understanding Array Modification

Modifying elements in an array allows you to change its contents after initialization. This can be done using direct assignments or through computations, as seen in the second phase of the exercise.

Modifications in this task include:

• `temp[0]` is re-calculated as `pow(temp[1], 3)`. Since `temp[1]` equals `3`, `temp[0]` becomes `27`.
• `temp[1]` is altered by subtraction: `temp[4] - temp[2]`, leading to a result of `12` because `18 - 6` equals `12`.
• `temp[2]` changes to `temp[0] - 5`, moving its value to `22` since `27 - 5` equals `22`.

Understanding how to modify array elements dynamically can greatly enhance the versatility of your code.

Calculating and Printing Output from Arrays

Output calculation is about using loops to extract and display the values stored in arrays. It's a simple yet crucial step often required to verify that program computations are correct.

In our exercise, we print the array contents twice: once after initialization and once after modification.

• The first print loop outputs: `2 3 6 11 18`. This confirms that the initialization worked as intended.
• After modifying the array, the next loop outputs: `27 12 22 11 18`. This print-out helps verify each modification's accuracy.

Utilizing loops for printing ensures all array elements are covered, providing a full view of their values at any point during execution.