Question

Can somebody explain me what this code does in a few or one sentence?#include #include using namespace std;int main () { const int NUM_ELEMENTS = 8; vector numbers(NUM_ELEMENTS); int i = 0; int tmpValue = 0; cout << "Enter " << NUM_ELEMENTS << " integer values..." << endl; for (i = 0; i < NUM_ELEMENTS; ++i) { cout << "Enter Value#" << i+1 << ": "; cin >> numbers.at(i); } for (i = 0; i < (NUM_ELEMENTS /2); ++i) { tmpValue = numbers.at(i); numbers.at(i) = numbers.at(NUM_ELEMENTS - 1 - i); numbers.at(NUM_ELEMENTS - 1 - i) = tmpValue; } system ("pause"); return 0;}

Answer 1

Answer:

The program declares and array of 8 elements and swap the position of the 1st element with the 8th; the 2nd with the 7th, the 3rd with the 6th and the 4th with the 5th element

Explanation:

First, I'll arrange the code line by line, then I'll start my explanation from the variable declaration at line 4

#include

using namespace std;

int main () {

const int NUM_ELEMENTS = 8;

vector numbers(NUM_ELEMENTS);

int i = 0;

int tmpValue = 0;

cout << "Enter " << NUM_ELEMENTS << " integer values..." << endl;

for (i = 0; i < NUM_ELEMENTS; ++i)

{

cout << "Enter Value#" << i+1 << ": "; cin >> numbers.at(i);

}

for (i = 0; i < (NUM_ELEMENTS /2); ++i)

{

tmpValue = numbers.at(i); numbers.at(i) = numbers.at(NUM_ELEMENTS - 1 - i);

numbers.at(NUM_ELEMENTS - 1 - i) = tmpValue;

}

system ("pause");

return 0;

}

Line 4: This line declares an instant constant variable NUM_ELEMENTS with a constant value of 8. Meaning that the value cannot be changed during program execution.

Line 5: This line declares a vector array that can change in size. Here, it was declared with size 8.

Line 6 & 7: These lines declares integers variables i and tmpValue with an initialised value of 0, each.

Line 8: This line prints the following string; Enter 8 integer values...

Line 9 to 12: These lines represent an iteration which starts from 0 to 7.

Side Note: When an array is being declared, the index starts from 0 and ends at 1 less that the array size.

So, during this iteration, it accepts inputs into the array from index 0 to 7 i.e. from the first element till the last

Line 13 to 17: This is also an iterative statement. But what this iteration does is that, it swaps elements of the array (as stated in the answer section)

The iteration starts from 0 and ends at a value less than NUM_ELEMENTS/2

Note that NUM_ELEMENTS = 2

So,we can conclude that the iteration starts from 0 till a value less that 8/2

Iteration: 0 till a value less that 4

So, that's 0 to 3 (the iteration is done on array element at index 0,1,2 and 3).

When iteration is at 0, the following is done

tmpValue = number at index 0 i.e. a temporary value is used to store the number at index 0 of the array

Number at 0 = number at (8-1-0)

i.e. number at 0 = number at (7)

Number at 7 is then equal to tmpValue

Swap Completed.

The same is done for index 1,2 and 3.