Question

include using namespace std; int main() { int j; int one[5]; int two[10]; for (j = 0; j < 5; j++) one[j] = 5 * j… # What is the output of the following program? #include using namespace std; int main() { int j; int one[5]; int two[10]; for (j = 0; j < 5; j++) one[j] = 5 * j + 3; cout << "One contains: "; for (j = 0; j < 5; j++) cout << one[j] << " "; cout << endl; for (j = 0; j < 5; j++) { two[j] = 2 * one[j] - 1; two[j + 5] = one[4 - j] + two [j]; } cout << "Two contains: "; for (j = 0; j < 10; j++) cout << two[j] << " "; cout << endl; return 0; }

Short answer

The program outputs arrays: 'One contains: 3 8 13 18 23' and 'Two contains: 5 15 25 35 45 28 33 38 43 48'.

Step-by-step solution

Initialize Arrays

The program starts by declaring two integer arrays: `one` with 5 elements and `two` with 10 elements. These arrays are used to store integer values.

Populate 'one' Array

A `for` loop is used to assign values to the array `one`. For each index `j` from 0 to 4, `one[j]` is set to `5 * j + 3`. - For `j = 0`: `one[0] = 5 * 0 + 3 = 3` - For `j = 1`: `one[1] = 5 * 1 + 3 = 8` - For `j = 2`: `one[2] = 5 * 2 + 3 = 13` - For `j = 3`: `one[3] = 5 * 3 + 3 = 18` - For `j = 4`: `one[4] = 5 * 4 + 3 = 23`

Output 'one' Array

The contents of the `one` array are printed. The output is: ``` One contains: 3 8 13 18 23 ```

Populate 'two' Array First Half

Another loop is responsible for populating the `two` array. The first five elements are set using the formula `two[j] = 2 * one[j] - 1`. - For `j = 0`: `two[0] = 2 * 3 - 1 = 5` - For `j = 1`: `two[1] = 2 * 8 - 1 = 15` - For `j = 2`: `two[2] = 2 * 13 - 1 = 25` - For `j = 3`: `two[3] = 2 * 18 - 1 = 35` - For `j = 4`: `two[4] = 2 * 23 - 1 = 45`

Populate 'two' Array Second Half

The second half of the `two` array (elements 5 to 9) are defined using the reverse elements in `one` and already computed values in `two`. For each `j`, `two[j + 5] = one[4 - j] + two[j]`. - For `j = 0`: `two[5] = one[4] + two[0] = 23 + 5 = 28` - For `j = 1`: `two[6] = one[3] + two[1] = 18 + 15 = 33` - For `j = 2`: `two[7] = one[2] + two[2] = 13 + 25 = 38` - For `j = 3`: `two[8] = one[1] + two[3] = 8 + 35 = 43` - For `j = 4`: `two[9] = one[0] + two[4] = 3 + 45 = 48`

Output 'two' Array

Finally, the values in `two` are printed. The output is: ``` Two contains: 5 15 25 35 45 28 33 38 43 48 ```

Key concepts

Array Initialization

Array initialization in C++ is a fundamental concept used to store multiple values of the same data type in a single variable. Arrays allow you to use a segmented space in memory to access values using indices, making them very efficient for handling multiple data points.

When you declare an array, you not only specify its type but also the number of elements it can hold. For instance, in our program, we initialize two arrays with int one[5]; and int two[10];. The first array 'one' can hold five integer elements, while 'two' can accommodate ten.

Initialization can be as simple as declaring the array with a size or by assigning initial values in a list format: int arr[3] = {1, 2, 3};. In the absence of an explicit initialization, arrays typically contain random garbage values. Thus, it is crucial to assign values to the elements before using them.

For Loops in C++

For loops in C++ provide a simple and effective way to iterate over sequences such as arrays. They execute a block of code a specified number of times, which is particularly useful for array assignment and operations.

The structure of a for loop consists of three parts:

• Initialization: Establish a starting point or counting variable.
• Condition: Determine how long the loop should keep running.
• Increment/Decrement: Change the counting variable after each iteration.

In the program, this logic is evident in these loops: for (j = 0; j < 5; j++) is used to fill the 'one' array with values. Here, j starts at 0, runs while j is less than 5, and increases by 1 with each iteration.

The second set of for loops populates the first and second halves of the 'two' array. Using for loops ensures each array element is tackled systematically without omission or error.

Standard Output in C++

Standard output in C++ is a mechanism that allows programs to produce output on the screen, helping users or developers understand what the program is doing. The most common way to achieve this is via the cout object from the iostream library.

Using cout, you can stream text and variable values to the console in a readable format. The insertion operator << is used to feed data into cout. Multiple data points can be output sequentially, making it convenient to display values of array elements.

In our context, to display the contents of the arrays, we use the command cout << "One contains: "; followed by a loop that outputs each element. The output is formatted across the screen by appending a space or newline as needed. Once processing concludes for each array, a newline with cout << endl; helps separate outputs, keeping the display clean and intuitive.