Initial commit

LinkedList.c

+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct node
+{
+	int x;
+	struct node* n;
+} node;
+
+typedef void (*callback)(node* x);
+
+
+node* create(int x,node* n)
+{
+
+    node*  insertnode = (node*)malloc(sizeof(node));
+    if(insertnode == NULL)
+    {
+        printf("Error with node.\n");
+        exit(0);
+    }
+    insertnode->x = x;
+    insertnode->n = n;
+
+    return insertnode;
+}
+
+
+node* beginning(node* head, int x)  //In this function, the head pointer needs to point to the next node.
+{
+      node* insertnode = create(x,head); // This is creating the next node
+      head = insertnode; // The variable head is being assigned to insertnode
+      return head; // The program will return head.
+}
+
+
+node* insertNodeAfter(node *head, int x, node* idnode)
+{
+   if(head == NULL || idnode == NULL) // The if statement is comparing if both pointers equal null. If they do equal null, the program will return null. 
+	return NULL;
+   node *pointer = head;
+   while(pointer != idnode)
+       pointer = pointer->n;
+
+   if(pointer != NULL) 
+   {
+	node* insertnode = create(x,pointer->n);
+	pointer->n = insertnode;
+	return head;
+   }
+   else
+   {
+        return NULL;
+   }
+
+}
+
+
+node* removefirstNode(node* head)
+{
+   if(head == NULL)
+        return NULL;
+   node *first = head;
+   head = head->n;
+   first->n = NULL;
+
+   if(first == head)
+        head = NULL;
+   free(first);
+   return head;
+}
+
+node* removeNode(node* head, node* hold)
+{
+    if(hold == NULL)
+	return NULL;
+    
+    if(hold->n == NULL)
+	return removefirstNode(head);  
+
+    node* point = head;
+    while(point != NULL)
+    {
+      if(point->n == hold)
+          break;
+          point = point->n;
+
+    }
+  
+     if(point != NULL)
+     {
+        node* spare = point->n;
+        point->n = spare->n;
+        spare->n = NULL;
+        free(spare);
+     }
+     return head;
+}
+void display(node* dis)
+{
+     if(dis != NULL)
+	  printf("%d ",dis->x);
+}
+
+node* find(node* head, int x)
+{
+
+	node *point = head;
+	while(point!=NULL)
+	{
+	    if(point->x == x)
+            {
+                return point;
+            }
+	    point = point->n;
+        }
+        return NULL;
+}
+
+
+void printlist(node * head) {
+    node * now = head;
+
+    while(now != NULL) {
+	printf("%d\n", now->x);
+	now = now->n;
+}
+}
+
+
+void traverse(node* head,callback a)
+{
+    node* locate = head;
+    while(locate != NULL)
+    {
+	a(locate);
+	locate = locate->n;
+    }
+}
+
+
+
+node* sortList(node* head)
+{
+     node *a, *b, *c;
+
+     a = head;
+     head = NULL;
+
+     while(a != NULL) // if a is equal to nothing, node c will equal to a and a will point to itself and the node n.
+     {
+	c = a;
+	a = a->n;
+	if (head != NULL)
+	{
+	    if(c->x > head->x)  //x is the integer variable for the node structure.If c point to x is less than head pointing to head, b gets assgined to head.
+	    {
+		b = head;
+		while  ((b->n != NULL && c->x > b->n->x)) // In the while loop, while b point to n is not equal to null and if c point to x is greater than b pointing to n pointing to x
+		{
+		     b = b->n; // b will point to n to compare the values
+		}
+		c->n = b->n; // c pointing to n would equal b pointing to n if the numbers need switching. 
+		b->n = c; // When the switch is finished, b pointing to n would equal to c
+             }
+	     else
+	     {
+		 c->n = head; // In the else statement, c pointing to n would equal to head if the numbers are finished switching places.
+		 head = c; // After the switching has finshed, c will pass the sorted list to head. 
+             }
+         }
+         else
+         {
+             c->n = NULL; // In the second else statement, c pointing to n will equal null if there are no switches made.
+             head = c;// c will pass the current state of the list to head.
+	 }
+      }
+      return head;
+}
+
+
+node* reverseList(node* head)
+{
+  node* first = NULL;
+  node* now = head;
+  node* n;
+  while (now != NULL)
+  {
+      n = now->n;
+      now->n = first;
+      first = now;
+      now = n;
+  }
+  head = first;
+  return head;
+
+}
+
+void menu()
+{
+     printf("0.menu\n");
+     printf("1. Insert some nodes into the list\n");
+     printf("2. Insert node after a previous node\n");
+     printf("3. Remove a node from the front of the list\n");
+     printf("4. Remove any node from the list\n");
+     printf("5. Sort the list\n");
+     printf("6. Reverse the linked list\n");
+     printf("-1.quit\n");
+
+
+}
+
+int main()
+{
+   
+	int instruction = 0;
+        int x;
+
+	node* head = NULL;
+        node* spare = NULL;
+	callback show = display;
+
+	menu();
+        while(1)
+        {
+	    printf("Enter a command(0-6,-1 to quit):");
+	    scanf("%d",&instruction);
+
+	   if(instruction == -1)
+		break;	
+	   switch(instruction)
+	   {
+	    case 0:
+		menu();
+		break;
+	    case 1:
+		printf("Enter 6 numbers into the list: ");
+		scanf("%d",&x);
+		head = beginning(head, x);
+		traverse(head,show);
+		break;
+	    case 2:
+		printf("Enter a number to insert after the previous number:");
+                scanf("%d",&x);
+		spare = find(head,x);
+		if(spare != NULL)
+		{
+		printf("Enter the value you wish to insert after:");
+		scanf("%d",&x, &spare);
+		head = insertNodeAfter(head, x, spare);
+                if(head != NULL)
+		    traverse(head,show);
+                }
+		else
+		{
+		      printf("The number %d does not exist",x);
+		}
+		break;
+	     case 3:
+		 head = removefirstNode(head);
+		 if(head != NULL)
+		     traverse(head,show);
+		 break;
+             case 4:
+		printf("Enter a number that you want to remove:");
+		scanf("%d",&x);
+		spare = find(head,x);
+		if(spare != NULL)
+		{
+		     removeNode(head,spare);
+                     if(head != NULL)
+		         traverse(head,show); 
+                }
+		else
+		{
+		     printf("The number %d does not exist",x);
+ 		}
+	        break;
+	     case 5:
+		 head = sortList(head);
+		 if(head != NULL)
+                     traverse(head,show);
+		 break;
+	     case 6:
+                  head = reverseList(head);
+		  if(head != NULL)
+		      traverse(head,show);
+		  break;
+             }
+		
+	}
+	return 0;
+}
\ No newline at end of file