Loop doesn't behave properly

Question

I have been stuck on this problem for too long now (6+ hours -_-).

I am trying to make a simple swimming class booking system in c++. I have completed 90% of it, the only thing that is giving me trouble is showing available time slots, specifically:

to display all time slots that are available for booking (An example is shown in Figure 2. In the figure, 'x' means no swimming instructor is available in the time slot, 'J/A/P/M/K' means J (Jeff), A (Anna), P(Peter), M (Michael) and K(Kerry) are all available in the time slot, 'J/A/P' means J (Jeff), A (Anna), and P(Peter) are all available in the time slot, but M (Michael) and K(Kerry) are not available in the time slot.)

For this task, I have created a "Get Availability" function inside of my "Schedule class" (I will try to explain it as I go). The function is as follows:

bool Schedule::GetAvailability(int day, int time, int trainer){

bool available;

    if(_bookingVector.empty()){
        return true;
    } else{
        for(int i = 0; i < _bookingVector.size(); ++i){

            int bTempTime = _bookingVector[i].GetTime();
            int bTempDay = _bookingVector[i].GetDay();
            int bTempTrainer = _bookingVector[i].GetTrainer();

            if((bTempTime == time) && (bTempDay == day) && (bTempTrainer == trainer)){
                available= false;
            }else{
                available= true;
            }
    }
}

return available;

}

All this method does is access a vector which stores individual bookings as objects of my "bookings" class. Each booking object contains a day, a time, and a trainer variable. This method loops through the vector and accesses each booking object to obtain the aforementioned information. It then checks the information against the parameters input when the method is called.

This works fine, I have checked it multiple times and it returns true/false correctly depending on this input.

I call this method in my display method which is:

void Schedule::DisplaySchedule(){


        // Create the 2d array
    std::string **table;
    table = new string*[_rows];
    for (unsigned int row = 0; row < _rows; row++){
        table[row] = new string[_cols];
    }

        //Fill 2d array with ""

    for(int row = 0; row < _rows; row++){
        for(int col = 0; col < _cols; col++){
            table[row][col] = "";
        }
    }
        //insert available trainers to correct cell

        for(unsigned int row = 0; row < _rows; row++){
            for(unsigned int col = 0; col < _cols; col++){
                for(unsigned int x = 0; x < sizeof(_trainers)/sizeof(_trainers[0]); x++){

             bool available = GetAvailability(col, row, x);

             if(available == true){
                table[row][col] += _trainers[x][0];
             }else{
                table[row][col] += "";
             }
        }


                }            
            }   


        //DisplayDebug(); //shows debugging display

       // Print out table
    cout << "---------------------------------------------------------------" << endl;
    for(unsigned int i = 0; i < ((sizeof(_days))/(sizeof(_days[0]))); i++){
        cout << setw(_width) << _days[i];
    }
    cout << endl;
    cout << "---------------------------------------------------------------" << endl;
    cout << endl;

    for(int row = 0; row < _rows; row++){
            int x = 0;
            cout << _timeslots[row];
        for (int col = 0; col < _cols; col++){
                cout << setw(_width) << table[row][col];
        }
        cout << endl;
    }

    delete table; //clean up
}

This function creates the table which shows the available trainers:

The relevant part of this function is this:

//insert available trainers to correct cell

for(unsigned int row = 0; row < _rows; row++){
    for(unsigned int col = 0; col < _cols; col++){
        for(unsigned int x = 0; x < sizeof(_trainers)/sizeof(_trainers[0]); x++){

             bool available = GetAvailability(col, row, x);

             if(available == true){
                table[row][col] += _trainers[x][0];
             }else{
                table[row][col] += "";
             }
        }

    }
}

The "row" loop iterates through each time slots, and the "col" loop iterates through each day. The last loop iterates through an array which contains the name of each trainer (in booking objects, the trainer is stored a number from 0 to 4, which corresponds with the position of trainer in the _trainers array (so, "0" would be jeff, "1" would be anna etc)):

std::string _trainers [5] = {"Jeff", "Anna", "Peter", "Micheal", "Kerry"};

So within that loop the "GetAvailability" function is called, with "row, col, and x" as the parameters.

In my head, this should work fine, every time I iterate through the this it should add the first letter of the available trainers name to the cell in the table. But that is not what it does.

It only works for one booking, so, if I make a booking at the first time-slot on a Monday, the out-put will be correct:

It shows that all other trainers are available in that specific time-slot, except jeff who has a booking. But now if I make a second booking with anna, (so same timeslots, on a monday, with anna) I get this output:

The booking with jeff is still saved (shown as day: 0, time:0, trainer:0 in the debug output above the table in the screenshot), but it shows up as available in the table. Anna is showing as booked.

I have been stuck on this for a very long time now, and can't figure out why this is happening. I have tried to hard code the trainer loop (aka: calling the function by manually typing the trainer number: bool availability0 = GetAvailability(col, row, 0);) which works, but is not something I really want to do.

I have tried creating a boolean array which would take the results from the "GetAvailability" function inside the trainer loop, but that did not work either, only the newest booking would give the result. So for instance: If I use the example of the bookings (a booking with jeff and anna at the same time lost and day) the boolean array should show:

{ false, false, true, true, true };

but instead it shows

{true, false, true, true, true };

I can only assume I am doing something wrong with my loops, but I can figure this out. Any help would be appreciated, and if any more information is required please let me know.

EDIT 1:

Thanks for the initial replies guys, really appreciate it. As you guys suggested, I changed the GetAvailability function to this:

bool Schedule::GetAvailability(int day, int time, int trainer){



        if(_bookingVector.empty()){
            return true;
        } else{
            for(int i = 0; i < _bookingVector.size(); ++i){

                int bTempTime = _bookingVector[i].GetTime();
                int bTempDay = _bookingVector[i].GetDay();
                int bTempTrainer = _bookingVector[i].GetTrainer();

                if((bTempTime == time) && (bTempDay == day) && (bTempTrainer == trainer)){
                    return false;
                }
        }
    }
    //cout << " RETURNING " << availible;

}

After altering the method, this is the result:

Now, nothing shows up in the table, any suggestions?

Answer 1

I cannot debug your code, but what strikes me is that in your Schedule::GetAvailability(...) method, when the method discovers the slot is booked for the trainer [eg if((bTempTime == time) && (bTempDay == day) && (bTempTrainer == trainer)){ available= false; }...] you should immediately return or exit the loop.

If there are other bookings present in the array after the one that matched, then available is reset to true. This is why it happens after more than one booking is present.

Answer 2

The logic used in the following lines is wrong:

if((bTempTime == time) && (bTempDay == day) && (bTempTrainer == trainer)){
    available= false;
}else{
    available= true;
}

Here's why:

if((bTempTime == time) && (bTempDay == day) && (bTempTrainer == trainer)){
    // At this point, you just need to return false
    // and not worry about checking other slots.
    // available= false;
    return false;

Given that, you don't need the else block. Those lines can simply be replaced by:

if((bTempTime == time) && (bTempDay == day) && (bTempTrainer == trainer)){
    return false;
}

Answer 3

You can make you for loop in method bool Schedule::GetAvailability(int day, int time, int trainer) as below.

  for(int i = 0; i < _bookingVector.size(); ++i){

        int bTempTime = _bookingVector[i].GetTime();
        int bTempDay = _bookingVector[i].GetDay();
        int bTempTrainer = _bookingVector[i].GetTrainer();

        if((bTempTime == time) && (bTempDay == day) && (bTempTrainer == trainer)){
            available= false;
        }else{
            available= true;
            break;
        }