Add node in sorted linked list

Question

I'm trying to make sorted linked list in ascending order , but for some reason the code give me one value if some one can tell me why I will be thankful see this function:

void AddNode(Node *&head){
 int temp;
 Node *q;
 Node *prev = 0; 
 Node *t;
 cout <<"enter a number : ";
 cin >> temp;
 t = new Node ;
 t->number = temp;
 t->next = 0;
 if (head == 0) {
 head = t;
 } else {
 q = head;
 while (q != 0 ){
 prev = q;
 if(q->number > t->number){
 prev->next = t;
 t->next = q;
 break; 
 }
 q = q->next; // counter 
 }
 if (q == 0 ) // if it is the last value
 q = t;
 }
 }

• Khalil Khalaf: That parameter?? It smells. Anyway If it compiles then you need to step-over your code to see what is exactly happening. Using F-10 on Visual Studio
• Igor Tandetnik: You don't update head when the new node is inserted in front. Also, q = t at the end doesn't do anything useful - you are updating a local variable but aren't using this new value.
• Thomas Matthews: @FirstStep: What should the OP do if using Eclipse or Code::Blocks? Maybe the OP should use a debugger? There are other IDEs besides Visual Studio.

Answer 1

Inserting at the end is wrong:

if (q == 0 ) // if it is the last value
 q = t; 

You just modify q but never update the link of the last element. You should try:

if (q==0) // past end of list
 prev->next = t; // next of last element is t

----------EDIT-------------

Your management of pointers through looping is wrong, the following works and should be much clear (only one pointer is used to move in the list):

if (head == 0) { // empty list
 head = t;
} else if (t->number < head->number) { // insert in first place
 t->next = head;
 head = t;
} else { // general case
 q = head;
 while (q->next != 0 && q->next->number<t->number) {
 q = q->next;
 }
 cout << "insert after " << q->number << endl;
 t->next = q->next;
 q->next = t;
}

• Jean-Baptiste Yunès: see my new (tested) solution