Question

I have a method to convert dec to bin

QList<bool> widgetInput::decToBin(int number)
{
        int remainder;
        QList<bool> result;
        if(number <= 1) {
            result << number;
            return result;
        }

        remainder = number%2;
        decToBin(number >> 1);
        result << remainder;


}

but unfortunately this method only holds one element in list .
but when I replace the “result << number” with “cout << number”
it will work.
could you please help me and let me know where is my exact problem?

regards.

Answer 1

On each recursive step, you are creating a new QList result; which is local to that step, then inserting the remainder into it. You don’t need recursion (and in general it should be avoided when iteration will do):

QList<bool> result;

while(number > 0) {
  result << number%2;
  number /=2;
}

// Edited to add: Just realized you would also have to reverse QList here.
//  Depends on it's interface.

return result;

or better yet, just use a standard container:

bitset<sizeof(int)*CHAR_BIT> bs(number);