Printing Elements of a Vector Forwards and Backwards

[ineedhelpnow]

Write a for loop to print all NUM_VALS elements of vector courseGrades, following each with a space (including the last). Print forwards, then backwards. End with newline. Ex: If courseGrades = {7, 9, 11, 10}, print:

7 9 11 10
10 11 9 7

Hint: Use two for loops. Second loop starts with i = NUMVALS - 1.Sample program:

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

int main() {
   const int NUM_VALS = 4;             
   vector<int> courseGrades(NUM_VALS); 
   int i = 0;                         

   courseGrades.at(0) = 7;
   courseGrades.at(1) = 9;
   courseGrades.at(2) = 11;
   courseGrades.at(3) = 10;

   <STUDENT CODE>

   return 0;
}

this is what i came up with

for(i=0;i<NUM_VALS;++i) {
    cout<<courseGrades.at(i)<<" ";
}
cout<<endl;
for(i=NUM_VALS-1;?;++i){
      cout<<courseGrades.at(i)<<" ";
}
cout<<endl;

what should my condition be for the second loop?

 

[I like Serena]

what should my condition be for the second loop?

What kind of condition can you come up with? (Wondering)

 

[Swag1]

I am also having trouble with this problem everything works until the second for loop. The issue is the second loop only outputs one number, which is the ten. I see the logical issue, but do not know how to make it work. Any suggestions?

 

[Opalg]

I am also having trouble with this problem everything works until the second for loop. The issue is the second loop only outputs one number, which is the ten. I see the logical issue, but do not know how to make it work. Any suggestions?

You could keep the same range of values for i as in the first loop. Then use it to output courseGrades.at(j), where j = NUM_VALS - 1 - i.

 

[Swag1]

Hmmm, we are only aloud to change the "<student code>" section. Also, I meant to put my code in before, but I guess it didn't work. What would you suggest if I can only add code to the "<student code>" section and cannot initialize a new variable? @opalg

for (i = 0; i < NUM_VALS; i++) {
      cout << courseGrades.at(i) << " ";
     
   }
   cout << endl;
   
   for (i = NUM_VALS - 1; i < NUM_VALS; ++i) {
      cout << courseGrades.at(i) << " ";

   }
cout << endl;

 

[mjm585]

You are decreasing the value of i because you are trying to write the numbers backwards, so this should work

for (i = 0; i < NUM_VALS; i++) {
      cout << courseGrades.at(i) << " ";
     
   }
   cout << endl;
   
   for (i = NUM_VALS - 1; i >= 0; i--) {
      cout << courseGrades.at(i) << " ";

   }
   cout << endl;