Question

Modify the program to double each number in the vector.

#include <iostream>
#include <vector>
using namespace std;

int main() {
   const int N=8;
   vector<int> nums(N); // User numbers
   int i=0; // Loop index
   cout << "\nEnter " << N << " numbers...\n";
   for (i = 0; i < N; ++i) {
      cout << i+1 << ": ";
      cin >> nums.at(i);
   }
   // Convert negatives to 0
   for (i = 0; i < N; ++i) {
      if (nums.at(i) < 0) {
         nums.at(i) = 0;
      }
   }
   // Print numbers
   cout << "\nNew numbers: ";
   for (i = 0; i < N; ++i) {
      cout << " " << nums.at(i);
   }
   cout << "\n";

   return 0;
}

Answer 1

Hi. According to the question, program should be modified to double each number in vector . The given program already contains a loop that convers negative numbers to 0.

So, it is unclear whether to keep this loop or remove it.(Since it is asked to modify the code)

However, two versions of the code along with sample output is added here. So, any code can be chosen based on requirement.

In the first version of code, no existing code is removed.Additional code is added to double each number in vector.

In the second version of code, one for loop is removed(converting negative numbers to 0) and additional code is added to double each number in vector.

Code Version-1( no existing code is removed):

#include <iostream>
#include <vector>
using namespace std;

int main() {
   const int N=8;
   vector<int> nums(N); // User numbers
   int i=0; // Loop index
   cout << "\nEnter " << N << " numbers...\n";
   for (i = 0; i < N; ++i) {
      cout << i+1 << ": ";
      cin >> nums.at(i);
   }
   // Convert negatives to 0
   for (i = 0; i < N; ++i) {
      if (nums.at(i) < 0) {
         nums.at(i) = 0;
      }
   }
   
   // Double each number in the vector
   for (i=0; i < N; ++i) {
       
       int num=nums.at(i);   //gets the value at index i and stores it in variable 'num'
       nums.at(i)=num*2;    //doubles the value of number at index i
       
   }
   
   // Print numbers
   cout << "\nNew numbers: ";
   for (i = 0; i < N; ++i) {
      cout << " " << nums.at(i);
   }
   cout << "\n";

   return 0;
}

Sample output:

Code Version-2(One for loop is removed):

#include <iostream>
#include <vector>
using namespace std;

int main() {
   const int N=8;
   vector<int> nums(N); // User numbers
   int i=0; // Loop index
   cout << "\nEnter " << N << " numbers...\n";
   for (i = 0; i < N; ++i) {
      cout << i+1 << ": ";
      cin >> nums.at(i);
   }
   
   // Double each number in the vector
   for (i=0; i < N; ++i) {
       
       int num=nums.at(i);   //gets the value at index i and stores it in variable 'num'
       nums.at(i)=num*2;    //doubles the value of number at index i
       
   }
   
   // Print numbers
   cout << "\nNew numbers: ";
   for (i = 0; i < N; ++i) {
      cout << " " << nums.at(i);
   }
   cout << "\n";

   return 0;
}

Sample output: