Binary search tree output file is not the expected output data - c

Question

Okay so I am creating a Binary Search Tree that reads in strings and stores them in the tree. I am trying to confirm that each string has it's own node and each string is actually being read in. When my program is run, I believe it is creating seven nodes, one for each of the strings in the input file. So I created an Output file that prints the string that was just read to make sure each string is being stored in a node. There are seven strings in my input file :
bring
awake
anger
carry
global
fixed
halt
Here is the code for my program:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXLEN 15
typedef struct treeNode{
char string[MAXLEN+1];
struct treeNode *left;
struct treeNode *right;
}treeNode;
treeNode * insert(treeNode *node, char s[MAXLEN]){
puts("running insert");
if(node == NULL){
node = (treeNode *)malloc(sizeof(treeNode));
strncpy(node -> string, s, MAXLEN);
node -> left = NULL;
node -> right = NULL;
}
else if(strcmp(node->string, s)>0){
node -> right = insert(node->right, s);
}
else if(strcmp(node->string, s)<0){
node -> left = insert(node->left, s);
}
else if(strcmp(node->string, s) == 0){
node -> left = insert(node->left, s);
}
return node;
}
int main(int argc, char *argv[]){
treeNode *root = NULL;
FILE *ifp;
FILE *ofp;
char s[MAXLEN+1];
if(argc != 3){
fprintf(stderr, "Usage: %s file\n", argv[1]); exit(1);
}
if((ifp = fopen(argv[2], "r")) == NULL){
fprintf(stderr, "Could not open file: %s\n", argv[2]); exit(1);
}
ofp = fopen("output.txt", "w+");
while(fscanf(ifp, "%s\n", &s) != EOF){
root = insert(root, s);
fprintf(ofp, "%s\n", root->string);
}
return 0;
}
And this is what the output file looks like after running the program:
bring
bring
bring
bring
bring
bring
bring
Now there are seven strings in each file so i am assuming each one is read. But how can I know if my program successfully created a node for each string?
How can I fix the problem? Any help would be appreciated! Thanks!

Answer 1

FULL CODE repaired : http://pastebin.com/5BTnxTcd
OTHER optimizing code , leave it to you.
It seem your problem is return. It need to be like this, because you need to return root of tree->
treeNode * insert(treeNode *node, char s[MAXLEN]){
puts("running insert");
if(node == NULL){
node = (treeNode *)malloc(sizeof(treeNode));
strncpy(node -> string, s, MAXLEN);
node -> left = NULL;
node -> right = NULL;
}
else if(strcmp(node->string, s)>0){
node -> right = insert(node->right, s);
}
else if(strcmp(node->string, s)<0){
node -> left = insert(node->left, s);
}
else if(strcmp(node->string, s) == 0){
node -> left = insert(node->left, s);
}
return node;
}
**EDIT: ** It seem you have problem also with argv, argv[0] is name of program
fprintf(stderr, "Usage: %s file\n", argv[1]); exit(1);
need to be
fprintf(stderr, "Usage: %s file\n", argv[0]); exit(1);
EDITEDIT :
You need function to do recursive process to tree, and output first left side then right and it will be:
void treeprint( treeNode *node , FILE *OUTPUT_FILE)
{
if ( node != NULL)
{
treeprint(node->left , OUTPUT_FILE);
fprintf(OUTPUT_FILE , "%s" , node->string);
treeprint(node->right, OUTPUT_FILE);
}
}
and call after while loop , and call function like treeprint(root, ofp);.

Answer 2

The issue is with how you are printing. In your insert algorithm, you never modify the string in the node. But, when you print, you are printing the root each time. So, you have a couple of choices:
Use a debugger as #JoachimPileborg suggested.
print the input string s to see if it was read from the input properly.
Write another function to traverse your tree and print out the string in each node as you go. This is the most involved, but is likely to be useful later.

Answer 3

Lets come to the issue you are facing:
You want to know if your program successfully created a node for each string or not. There are more than one ways to tackle this problem. The easiest way is to print out the value of the node when it is actually being created. Thus your code will look something like:
treeNode * insert(treeNode *node, char s[MAXLEN]){
puts("running insert");
if(node == NULL){
node = (treeNode *)malloc(sizeof(treeNode));
strncpy(node -> string, s, MAXLEN);
node -> left = NULL;
node -> right = NULL;
**printToFile( root->string );**
}
else if(strcmp(node->string, s)>0){
node -> right = insert(node->right, s);
}
else if(strcmp(node->string, s)<0){
node -> left = insert(node->left, s);
}
else if(strcmp(node->string, s) == 0){
node -> left = insert(node->left, s);
}
return node;
}
Here is helper function for printing into file:
File* ofp; // Need to be declared globally or pass in functions as parameters
void openWritableFile()
{
ofp = fopen("output.txt", "w+");
}
void printToFile( char* data )
{
fprintf(ofp, "%s\n", data );
}
Another approach would be to travel the whole tree using tree traversal algorithms such as in-order, post-order or pre-order, but only after creation of the complete tree.
Here is how you can do inorder traversal by using your root element and thus printing contents of the tree:
void inorder(struct root* node)
{
if (root == NULL)
return;
inorder(root->left)
printToFile( root->string );
inorder(root->right);
}
You can learn about tree traversal here: Tree Traversal