How to reset to the beginning of a linked list?

I have a function that will look something like this:

Code:

---

void function(node* root, int num)
{
    int i = 0;
   
    while(i < 10)
    {
        while(root->data != num || root != NULL)
        {
            root->next;
        }
        if(root->data == num)
        {
            root->count++;
            i++;
        }
    }
}

---

How do I get it so I can check root from the beginning of the list every time and still keep the updated count value??

Keep an extra pointer to save the original root.

Code:

---

while (i < 10)
{
    node* save = root;
    ...
    root = save;
}

---

Now the middle part will always start at "root"

Quote:

---

Originally Posted by whiteflags

Keep an extra pointer to save the original root.

Code:

---

while (i < 10)
{
    node* save = root;
    ...
    root = save;
}

---

Now the middle part will always start at "root"

---

Will that keep the update of count?

It should. Right now your code will update count on the node whose data matches num. You're simply resetting the value of the root pointer to what it was before you started -- which does not mean anything for the dereferenced values.

Use a temp variable.

Every time you wish to reset the list, change the temp variable back to the location entered into the function.

Then I do not understand what is wrong with this:

Code:

---

void pickDoubleMu(teams * sPtr, matchups * head)
{
    int i = 0;
    char *outputText = "output.txt";
    FILE *output = fopen(outputText, "w");
    int randMu;
    int j = 0, k;
    matchups *temp;
    teams *team;
    teams *other;
   
    int usedMu[20];
    while(i < 20)
    {
        temp = head;
        team = sPtr;
        other = sPtr;

        randMu = rand() % 45;
        for(j = 0; j <= randMu; j++)
        {
            temp = temp->next;
        }
        if(temp->count == 0)
        {
            temp->count++;
            while(temp->team1 != team->num)
            {
                team = team->next;
            }
            if(team->count < 4)
            {
                team->count++;
                while(temp->team2 != other->num)
                {
                    other = other->next;
                }
                if(other->count < 4)
                {
                    other->count++;
                }                           
            }
        }

        if(team->count <= 1 && other->count <=4 && team->count <=4)
        {
            usedMu[i] = temp->num;
            i++;
        }
    }
    for(k = 0; k < 20; k++)
    {
       
        temp = head;
        while(usedMu[k] != temp->num)
            temp = temp->next;
        fprintf(output, "%d\t%d\t%d\t%d\n", usedMu[k], temp->team1, temp->team2, temp->count);
    }

}

---

It will either segfault or print duplicate values.. I want there to be no duplicates in temp->num, and each team(team->num) should be used 4 times. This will produce duplicates or infinite loop. I've been working on this program for so long and can not get it working

Going back to the simple function, and my simple answer:

Code:

---

while (i < 10)
{
    node* save = root;
    ...
    root = save;
}

---

You realize that you wouldn't otherwise touch "save", right? If you change the temp pointer in your function, as you are, then it won't serve its purpose.

Well if it's crashing with a segfault, then run it in the debugger and it will point you at the line of code causing the problem.

For me, all your unchecked temp = temp->next; constructs are dangerous. If you run into the end of the list by mistake, then this just blows up.

Code:

---

        for(j = 0; temp != NULL && j <= randMu; j++)
        {
            temp = temp->next;
        }
        // check temp is not NULL

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