Question

I want to generate unique random numbers and add item in function of these random numbers. Here is my code :

The problem is when i verify if the number generated exist in the array with the code results.contains(randomNb) :

   int nbRandom = ui->randoomNumberSpinBox->value();
   //nbRandom is the number of the random numbers we want
   int i = 1;
   int results[1000];
   while ( i < nbRandom ){
       int randomNb = qrand() % ((nbPepoles + 1) - 1) + 1;
       if(!results.contains(randomNb)){
           //if randomNb generated is not in the array...
           ui->resultsListWidget->addItem(pepoles[randomNb]);
           results[i] = randomNb;
           //We add the new randomNb in the array
           i++;
       }
   }

Answer 1

results is an array. That’s a built-in C++ type. It’s not a class type and doesn’t have methods. So this can’t work:

results.contains(randomNb)

You probably want to use a QList instead. Like:

QList<int> results;

Add elements to it with:

results << randomNb;

Also, you have an off-by-one error in the code. You start counting from 1 (i = 1) instead of 0. This will result in missing the last number. You should change the i initialization to:

int i = 0;

With the changes, your code would become:

int nbRandom = ui->randoomNumberSpinBox->value();
//nbRandom is the number of the random numbers we want
int i = 0;
QList<int> results;
while ( i < nbRandom ){
    int randomNb = qrand() % ((nbPepoles + 1) - 1) + 1;
    if(!results.contains(randomNb)){
        //if randomNb generated is not in the array...
        ui->resultsListWidget->addItem(pepoles[randomNb]);
        results << randomNb;
        //We add the new randomNb in the array
        i++;
    }
}