Question

I’m having trouble inserting a struct into a linked list in numerical order. Each struct has a “number” as indicated in the code below. I’m trying to have the struct with the lowest number be the head of the list (ie: be the struct pointed to by “people”). I’ve been staring at this code on and off all day and I can’t figure out what’s wrong with it. Any help is much appreciated. Thanks

Person *addPerson(Person *people, Person *addition, int &numList)
{
if (people == NULL && numList == 0)
{
    people = addition;
    numList++;
    return people;
}
if (people->number >= addition->number)
{
    addition->nextPerson = people;
    people = addition;
    return people;
}
else if (people->number < addition->number && people->nextPerson != NULL)
{
    addPerson(people->nextPerson, addition, numList);
}
else if (people->number < addition->number && people->nextPerson == NULL)
{
    people->nextPerson = addition;
    numList++;
    return people;
}
}

EDIT**

int main()
{
Person *blake = new Person;
Person *kyra = new Person;
Person *elon = new Person;
Person *bill = new Person;
Person *people = NULL;

blake->number = 1;
blake->name = "blake";
blake->lastName = "madden";
blake->nextPerson = NULL;

kyra->number = 2;
kyra->name = "kyra";
kyra->lastName = "madden";
kyra->nextPerson = NULL;

elon->number = 3;
elon->name = "elon";
elon->lastName = "musk";
elon->nextPerson = NULL;

bill->number = 4;
bill->name = "bill";
bill->lastName = "gates";
bill->nextPerson = NULL;

int num = 0;
int &numList = num;

people = addPerson(people, blake, numList);

people = addPerson(people, kyra, numList);
people = addPerson(people, elon, numList);
people = addPerson(people, bill, numList);

cout << people->name << '\n' << people->lastName;
}

Answer 1

You are not using the return value from addPerson() in the third if block. Try:

people->nextPerson = addPerson(people->nextPerson, addition, numList);
return people;

You also need the return people; in there otherwise you’ll run off the end of your function and not return anything sensible (my compiler warned me about that, you should change your warning settings so yours does too).

With the above change, your code appears to run correctly.