initial the labs' work

week3/DLList.c

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+// DLList.c - Implementation of doubly-linked list ADT
+// Written by John Shepherd, March 2013
+// Modified by John Shepherd, August 2014, August 2015
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include "DLList.h"
+
+// data structures representing DLList
+
+typedef struct DLListNode {
+	char   *value;  // value of this list item (string)
+	struct DLListNode *prev;
+	               // pointer previous node in list
+	struct DLListNode *next;
+	               // pointer to next node in list
+} DLListNode;
+
+typedef struct DLListRep {
+	int  nitems;      // count of items in list
+	DLListNode *first; // first node in list
+	DLListNode *curr;  // current node in list
+	DLListNode *last;  // last node in list
+} DLListRep;
+
+// create a new DLListNode (private function)
+static DLListNode *newDLListNode(char *it)
+{
+	DLListNode *new;
+	new = malloc(sizeof(DLListNode));
+	assert(new != NULL);
+	new->value = strdup(it);
+	new->prev = new->next = NULL;
+	return new;
+}
+
+// create a new empty DLList
+DLList newDLList()
+{
+	struct DLListRep *L;
+
+	L = malloc(sizeof (struct DLListRep));
+	assert (L != NULL);
+	L->nitems = 0;
+	L->first = NULL;
+	L->last = NULL;
+	L->curr = NULL;
+	return L;
+}
+
+// free up all space associated with list
+void freeDLList(DLList L)
+{
+	assert(L != NULL);
+	DLListNode *curr, *prev;
+	curr = L->first;
+	while (curr != NULL) {
+		prev = curr;
+		curr = curr->next;
+		free(prev->value);
+		free(prev);
+	}
+	free(L);
+}
+
+// trim off \n from strings (private function)
+// this is needed for getDLList() because of fgets()
+// alternatively, we could use the evil gets() function
+static char *trim(char *s)
+{
+	int end = strlen(s)-1;
+	if (s[end] == '\n') s[end] = '\0';
+	return s;
+}
+
+// create an DLList by reading items from a file
+// assume that the file is open for reading
+// assume one item per line, line < 999 chars
+DLList getDLList(FILE *in)
+{
+	DLList L;
+	DLListNode *new;
+	char line[1000];
+
+	L = newDLList();
+	while (fgets(line,1000,in) != NULL) {
+		char *value = strdup(trim(line));
+		new = newDLListNode(value);
+		if (L->last == NULL) {
+			L->first = L->last = new;
+		}
+		else {
+			L->last->next = new;
+			new->prev = L->last;
+			L->last = new;
+		}
+		L->nitems++;
+	}	
+	L->curr = L->first;
+	return L;
+}
+
+// display list to file, one item per line
+// assumes that the file is open for writing
+void putDLList(FILE *out, DLList L)
+{
+	assert(out != NULL); assert(L != NULL);
+	DLListNode *curr;
+	for (curr = L->first; curr != NULL; curr = curr->next)
+		fprintf(out,"%s\n",curr->value);
+}
+
+// check sanity of a DLList (for testing)
+int validDLList(DLList L)
+{
+	if (L == NULL) {
+		fprintf(stderr,"DLList is null\n");
+		return 0;
+	}
+	if (L->first == NULL) {
+		// list is empty; curr and last should be null
+		if (L->last != NULL || L->curr != NULL) {
+			fprintf(stderr,"Non-null pointers in empty list\n");
+			return 0;
+		}
+	}
+	else {
+		// list is not empty; curr and last should be non-null
+		if (L->last == NULL || L->curr == NULL) {
+			fprintf(stderr,"Null pointers in non-empty list\n");
+			return 0;
+		}
+	}
+	int count;
+	DLListNode *curr;
+	// check scanning forward through list
+	count = 0;
+	for (curr = L->first; curr != NULL; curr = curr->next) {
+		if (curr->prev != NULL && curr->prev->next != curr) {
+			fprintf(stderr, "Invalid forward link into node (%s)\n",curr->value);
+			return 0;
+		}
+		if (curr->next != NULL && curr->next->prev != curr) {
+			fprintf(stderr, "Invalid backward link into node (%s)\n",curr->value);
+			return 0;
+		}
+		count++;
+	}
+	if (count != L->nitems) {
+		fprintf(stderr, "Forward count mismatch; counted=%d, nitems=%d\n",
+		        count, L->nitems);
+		return 0;
+	}
+	// check scanning backward through list
+	count = 0;
+	for (curr = L->last; curr != NULL; curr = curr->prev) {
+		count++;
+	}
+	if (count != L->nitems) {
+		fprintf(stderr, "Backward count mismatch; counted=%d, nitems=%d\n",
+		        count, L->nitems);
+		return 0;
+	}
+	// nothing went wrong => must be ok
+	return 1;
+}
+
+// return item at current position
+char *DLListCurrent(DLList L)
+{
+	assert(L != NULL); assert(L->curr != NULL);
+	return L->curr->value;
+}
+
+// move current position (+ve forward, -ve backward)
+// return 1 if reach end of list during move
+// if current is currently null, return 1
+int DLListMove(DLList L, int n)
+{
+	assert(L != NULL);
+	if (L->curr == NULL)
+		return 1;
+	else if (n > 0) {
+		while (n > 0 && L->curr->next != NULL) {
+			L->curr = L->curr->next;
+			n--;
+		}
+	}
+	else if (n < 0) {
+		while (n < 0 && L->curr->prev != NULL) {
+			L->curr = L->curr->prev;
+			n++;
+		}
+	}
+	return (L->curr == L->first || L->curr == L->last) ? 1 : 0;
+}
+
+// move to specified position in list
+// i'th node, assuming first node has i==1
+int DLListMoveTo(DLList L, int i)
+{
+	assert(L != NULL); assert(i > 0);
+	L->curr = L->first;
+	return DLListMove(L, i-1);
+}
+
+// insert an item before current item
+// new item becomes current item
+void DLListBefore(DLList L, char *it)
+{
+	assert(L != NULL); 
+	// COMPLETE THIS FUNCTION
+}
+
+// insert an item after current item
+// new item becomes current item
+void DLListAfter(DLList L, char *it)
+{
+	assert(L != NULL); 
+	// COMPLETE THIS FUNCTION
+}
+
+// delete current item
+// new item becomes item following current
+// if current was last, current becomes new last
+// if current was only item, current becomes null
+void DLListDelete(DLList L)
+{
+	assert (L != NULL);
+	// COMPLETE THIS FUNCTION
+}
+
+// return number of elements in a list
+int DLListLength(DLList L)
+{
+	return (L->nitems);
+}
+
+// is the list empty?
+int DLListIsEmpty(DLList L)
+{
+	return (L->nitems == 0);
+}
+

week3/DLList.h

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+// DLList.h - Interface to doubly-linked list ADT
+// Written by John Shepherd, March 2013
+// Last modified, August 2014
+
+#ifndef DLLIST_H
+#define DLLIST_H
+
+#include <stdio.h>
+#include "DLList.h"
+
+// External view of DLList
+// Implementation given in DLList.c
+// Implements a DLList of strings (i.e. items are strings)
+
+typedef struct DLListRep *DLList;
+
+// create a new empty DLList
+DLList newDLList();
+
+// free up all space associated with list
+void freeDLList(DLList);
+
+// create an DLList by reading items from a file
+// assume that the file is open for reading
+DLList getDLList(FILE *);
+
+// display list to file, one item per line
+// assumes that the file is open for writing
+void putDLList(FILE *, DLList);
+
+// check sanity of a DLList (for testing)
+int validDLList(DLList);
+
+// return item at current position
+char *DLListCurrent(DLList);
+
+// move current position (+ve forward, -ve backward)
+// return 1 if reach end of list during move
+int DLListMove(DLList, int);
+
+// move to specified position in list
+// i'th node, assuming first node has i==1
+int DLListMoveTo(DLList, int);
+
+// insert an item before current item
+// new item becomes current item
+void DLListBefore(DLList, char *);
+
+// insert an item after current item
+// new item becomes current item
+void DLListAfter(DLList, char *);
+
+// delete current item
+// new item becomes item following current
+// if current was last, current becomes new last
+// if current was only item, current becomes null
+void DLListDelete(DLList);
+
+// return number of elements in a list
+int DLListLength(DLList);
+
+// is the list empty?
+int DLListIsEmpty(DLList);
+
+#endif

week3/Makefile

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+# COMP1927 16s2 Week 04 Lab
+
+CC=gcc
+CFLAGS=-Wall -Werror
+BINS=testL myed
+
+all: $(BINS)
+
+testL : testList.o DLList.o
+	$(CC) -o testL testList.o DLList.o
+
+myed : myed.o DLList.o
+	$(CC) -o myed myed.o DLList.o
+
+DLList.o : DLList.c DLList.h
+
+myed.o : myed.c DLList.h
+
+testList.o : testList.c DLList.h
+
+clean:
+	rm -f $(BINS) *.o core