How do I output the positive elements in the vector in reverse order?-CodePudding

I have the correct answer but it's just in the wrong order and I'm not sure how to reverse it. I can't add anything before for (int i = 1; i < inputVector.size(); i ) {

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

int main() {
   int i;
   vector<int> inputVector;
   int value;

   cin >> value;
   while (value != -1) {
      inputVector.push_back(value);
      cin >> value;
   }

   for (int i = 1; i < inputVector.size(); i  ) {
      if (inputVector[i] > 0) {
         cout << inputVector[i] << " " << endl;
      }
   }

   return 0;
}

CodePudding user response：

Instead of this:

   for (int i = 1; i < inputVector.size(); i  ) {
      if (inputVector[i] > 0) {
         cout << inputVector[i] << " " << endl;
      }
   }

Because your index i starts at 1, you are actually skipping the first element at inputVector[0]. I'm not sure why. But to print the list in reverse, you can adjust the index value by subtracting i from the index of the last element (size - 1).

   for (size_t i = 0; i < inputVector.size(); i  ) {
      size_t j = inputVector.size() - 1 - i;
      if (inputVector[j] > 0) {
         cout << inputVector[j] << " " << endl;
      }
   }

Vector also has a reverse iterator. So you can also do this:

for (auto itor = inputVector.rbegin(); itor != inputVector.rend(); itor  ) {

    int value = *itor;
    if (value > 0) {
       cout << value << " " << endl;
    }

}

CodePudding user response：

This should be sufficient given your contraints.

 for (int i = inputVector.size() - 1; i > 0 ; i  )
      if (inputVector[i] > 0) 
         cout << inputVector[i] << " " << endl;