Question

The following C++ code has a problem where the loop can exceed the size of the array if the user inputs too many numbers.

#include <iostream> using namespace std;

int main() {

int nums[20] = { 0 };

int a[10] = { 0 };

cout << a << endl;

cout << nums << endl;

cout << "How many numbers? (max of 10)" << endl; cin >> nums[0];
for (int i = 0; i < nums[0]; i++)
{

cout << "Enter number " << i << endl;

cin >> a[i]; }

// Output the numbers entered

for (int i = 0; i < 10; i++) cout << a[i] << endl;

return 0; }

If this program is run and we enter 255 for how many numbers, and 9 for every single number, then the program does something like this:

How many numbers? (max of 10)
255
Enter number 0
9

Enter number 1
9
Enter number 2
9

Enter number 3
9
Enter number 4
9

Enter number 5
9
Enter number 6
9

Enter number 7
9
Enter number 8
9

Enter number 9
9
Enter number 10
9

Enter number 11
9
Enter number 12
9

9
9
9
9
9
9
9
9
9
(Program may crash at this point, or possibly just exit)

Your results may vary, depending on what compiler, operating system, and CPU that you are using. If the program does not crash on your compiler, try it on transformer or the Windows machines in the lab and you should get the behavior shown above.

Why didn't the program loop 255 times? Your answer should be detailed and reference the way in which memory is organized and what is put into memory.

I don't really understand how memory works. Could somehow help me understand what is going on when this program runs in memory?

Answer 1

#include <iostream>
using namespace std;

int main() {

int nums[20] = { 0 };

int a[10] = { 0 };
int n;//reading size into n

cout << a << endl;

cout << nums << endl;

//reading size into separate variable
cout << "How many numbers? (max of 10)" << endl;
cin >> n;
for (int i = 0; i < n; i++)
{

cout << "Enter number " << i << endl;

cin >> a[i];
  
}

// Output the numbers entered

for (int i = 0; i < n; i++) cout << a[i] << endl;

return 0;
  
}

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