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Editorial Team
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Asked: 2026-05-26T16:22:30+00:00

My program simulates a video store. In my list there are multiple copies of

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My program simulates a video store. In my list there are multiple copies of some videos. If I try to rent a video and the first copy of that video in the list is already rented, my program fails to continue checking to see if the other copies are available (a film is available if custId is ‘0000’). Take a look at the text file from where the list gets its members for a better understanding of what i’m describing:

enter image description here

Could anyone take a look and let me know if they spot an issue? Any help is appreciated, thanks.

Code from main

 try
 {
     int index = 0;
     bool found = false;

     while (!found)
     {
         if (strncmp(filmId,filmList.getAt(index).number,6) == 0 && strncmp("0000",filmList.getAt(index).rent_id,5) == 0)//If that film is rented by NO customer
         {
             found = true;//customer can rent it

             strcpy(newItem.number,filmId);//copy filmId into newItem
             filmList.retrieve(newItem);//copy the struct in our orderedList with the same filmId/copy into newItem
             filmList.remove(newItem);//delete the struct with same filmId/copy as newItem from the orderedList
             strcpy(newItem.rent_id,custId);//update info in
             strcpy(newItem.rent_date,rentDate);//           newItem to show
             strcpy(newItem.return_date,dueDate);//                          that it has been rented
             filmList.insert(newItem);//put NewItem into list, effectivily replacing the removed item.

             cout << "Rent confirmed!" << endl;
         }
         else
         {
             if (strncmp(filmId,filmList.getAt(index).number,6) > 0 || strncmp("0000",filmList.getAt(index).rent_id,5) > 0)
             {
                 ++ index;
             }
             else
             {
                 throw string ("Not in list");
             }
         }
     }
 }
 catch (string s)
 {
     cout << "\n***Failure*** " << s << endl;
 }

Let me know if more code is required from any other parts of the program.

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1 Answer

  1. Editorial Team

    Here’s my best guess with the code provided.

    Let’s say we are looking up 101001Casablanca, therefore I’m assuming filmId = “101001Casablanca”. Also, assume the 101001Casablanca is checked out to customer 0001. We are comparing the first 6 characters of filmId to filmList.getAt(index).number, which I’m going to assume is at the very least “101001”. This passes, but since it is checked out the second condition fails.

    In the else we check the same strings in the first condition and still get 0 returned from strncmp which is false. The second condition is also false since strncmp(“0000”, “0001”, 5) is -1. Therefore we go to the final else which throws.

    If you are only checking string equality with strncmp, remember that it can return -1, therefore check if equal or not equal to 0.

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