cleanup

changed NODE_ERR to NODE_INT (and member 'err' to 'num')
commented most functions
updated traverse to return an error code, and others to check for it
makefile has 'gitindex' target, to add all code to git's index
makefile automatically converts spaces to tabs before compiles and gitindex
added .gitignore

.gitignore

+*.out

Makefile

 run : main.out
 	./main.out
 
-.PHONY : run compile test tabify
+.PHONY : run all test tabify
 
-test.out : llist.c llist.h test.c
+test.out : tabify llist.c llist.h test.c
 	gcc -ggdb -std=c99 -o test.out llist.c test.c
 
-main.out : llist.c llist.h main.c
+main.out : tabify llist.c llist.h main.c
 	gcc -std=c99 -o main.out llist.c main.c
 
-compile : test.out main.out
+all : test.out main.out
 
 test : test.out
 	./test.out
 
-tabify : *.h
+tabify : *.h *.c
 	for file in *.c *.h;\
 	do\
 	  unexpand -t4 --first-only $$file >temp ;\
 	  mv temp $$file;\
 	done
+
+gitindex : tabify *.c *.h
+	git add *.c *.h

llist.c

@@ -3,6 +3,7 @@
 #include "llist.h"
 
 void print_node_at(NODE *head, int pos){
+//prints by index
 	NODE *currentNode;
 
 	currentNode = head;
@@ -14,11 +15,10 @@ void print_node_at(NODE *head, int pos){
 }
 
 void print_node(NODE *head){
+//prints head
 	printf("%d\n", head->data);}
 
 void print_list(NODE *head){
-//	printf("Printing list...\n");
-
 	NODE *currentNode;
 	currentNode = head;
 
@@ -31,33 +31,42 @@ void print_list(NODE *head){
 	}
 }
 
-NODE_ERR psearch(NODE *head, datatype data){
+NODE_INT psearch(NODE *head, datatype data){
+//return:
+// positive : index where data was found; NODE* return is pointer to where
+// -1 : not found; NODE* return is NULL
 	printf("Searching list for: %d\n", data);
-	NODE_ERR node = search(head, data);
+	NODE_INT node = search(head, data);
 	if(node.node != NULL)
-		printf("Location found, index: %d.\n", node.err);
+		printf("Location found, index: %d.\n", node.num);
 	else
 		puts("Not found in this list.");
 	return node;
 }
 
-NODE_ERR search(NODE *head, datatype data){
-	NODE_ERR curr;
+NODE_INT search(NODE *head, datatype data){
+//return:
+// positive : index where data was found; NODE* return is pointer to where
+// -1 : not found; NODE* return is NULL
+	NODE_INT curr;
 	curr.node = head;
 	int i;
 	for(i=0;curr.node != NULL;i++){
 		if(curr.node->data == data){
-			curr.err=i;
+			curr.num=i;
 			return curr;
 		}
 		curr.node=curr.node->next;
 	}
 	curr.node = NULL;
-	curr.err = -1;
+	curr.num = -1;
 	return curr;
 }
 
 NODE *construct(datatype data, NODE *next){
+//return:
+// pointer to new node : normal
+// NULL : malloc failed
 	NODE *out = malloc(sizeof(NODE));
 	if(out != NULL){
 		out->data = data;
@@ -66,20 +75,33 @@ NODE *construct(datatype data, NODE *next){
 	return out;
 }
 
-NODE *traverse(NODE *head, int pos){
+NODE_INT traverse(NODE *head, int pos){
+//return:
+// 0 : normal
+// 1 : head is null; NODE* return is NULL
+// 2 : reached end of list; NODE* return is final element
+	NODE_INT out;
+	out.node = head;
+	out.num = 1;
 	if(head==NULL)
-		return NULL;
+		return out;
 	int i;
+	out.num = 0;
 	for(i=0;i<pos || pos<0;i++){
-		if(head->next != NULL)
-			head = head->next;
-		else
+		if(out.node->next != NULL)
+			out.node = out.node->next;
+		else{
+			out.num = 2;
 			break;
 		}
-	return head;
+	}
+	return out;
 }
 
 int delete_node_after(NODE *head){
+//return:
+// 0 : normal
+// 1 : head is NULL, or head->next is NULL, which means no node after to delete
 	if(head==NULL || head->next == NULL)
 		return 1;
 	NODE* tmp = head->next;
@@ -97,6 +119,9 @@ void delete_list(NODE *head){
 }
 
 NODE *construct_list(datatype list[], int size){
+//return:
+// pointer to head : normal
+// NULL : malloc failed
 	if(size<=0)
 		return NULL;
 	NODE *next = construct(list[size-1],NULL);
@@ -116,10 +141,20 @@ int add_to_end(NODE *head, datatype new_data){
 }
 
 int insert_node(NODE *head, int pos, datatype new_data){
+//return:
+// 0 : normal
+// 1 : head is NULL
+// 2 : malloc failed
+// 3 : pos is larger than length(head)
 	if(head==NULL)
 		return 1;
-	if(pos!=0)
-		return insert_node_after(traverse(head,pos-1),new_data);
+	if(pos!=0){
+		NODE_INT traverseResult = traverse(head,pos-1);
+		int insertResult;
+		if(traverseResult.num == 2 && pos > 0)
+			return 3;
+		return insert_node_after(traverseResult.node,new_data);
+	}
 	else{
 		int out = insert_node_after(head,head->data);
 		if(out>0)
@@ -130,6 +165,10 @@ int insert_node(NODE *head, int pos, datatype new_data){
 }
 
 int insert_node_after(NODE *head, datatype data){
+//return:
+// 0 : normal
+// 1 : head is NULL
+// 2 : malloc failed
 	if(head==NULL)
 		return 1;
 	NODE *new = construct(data, head->next);
@@ -141,6 +180,7 @@ int insert_node_after(NODE *head, datatype data){
 
 
 int length(NODE *head){
+//returns length of list
 	if(head==NULL)
 		return 0;
 	int i=1;

llist.h

@@ -6,19 +6,20 @@ typedef struct Node
 	struct Node *next;
 }NODE;
 
-typedef struct Node_Err
+typedef struct Node_Int
 {
   NODE *node;
-  int err;
-}NODE_ERR;
+  int num;
+}NODE_INT;
 
 void print_node_at(NODE *head, int pos);
 void print_list(NODE *head);
 void print_node(NODE *head);
-NODE_ERR psearch(NODE *head, datatype data);
-NODE_ERR search(NODE *head, datatype data);
+NODE_INT psearch(NODE *head, datatype data);
+NODE_INT search(NODE *head, datatype data);
 NODE *construct(datatype data, NODE *next);
-NODE *traverse(NODE *head, int pos);
+NODE_INT traverse(NODE *head, int pos);
+//NODE_INT traverse_before(NODE *head, int pos, int before);
 int delete_node_after(NODE *head);
 void delete_list(NODE *head);
 //int delete_node_at(NODE *head, int pos);

test.c

@@ -19,8 +19,8 @@ int main(){
 	print_list(root);
 	printf("The head is still at %p.\n", root);
 	puts("Searching for 5...");
-	NODE_ERR target = search(root, 5);
-	printf("I found it at index %d.\n", target.err);
+	NODE_INT target = search(root, 5);
+	printf("I found it at index %d.\n", target.num);
 	fputs("The number I found there was: ", stdout);
 	print_node(target.node);
 	puts("Deleting list...");