a question about which

Hey, I'm trying to write a which function, I've gotten most of it down:

#include "sh.h"
#include <stdio.h>
#include <dirent.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

int which1(char *dir, char *sub_dir);

int main()
{
  DIR *pdir;
  struct pathelement *pathlist;
  int i = 0;
  int result;
  struct dirent *pfile;
  char *dir, *subdir, *full;
  pathlist = get_path();
  pdir = opendir("/usr/bin/");

  if(NULL == pdir)
    {
      printf("Error Opening Directory\n");
      exit(0);
    }

  while(pathlist!=NULL){
    while(pfile = readdir(pdir)){
      result = which1(pfile->d_name, "ls");

      if(result){
        full = strcat(pathlist->element, "/ls");
        printf("%s\n", full);
        exit(1);
      }
    }
    pathlist = pathlist->next;
  }

  return 0;
}

int which1(char *dir, char *sub_dir){
 int result = 0;

  if(!(strcmp(sub_dir, dir)))
    result = 1;

  return result;
}

The actual looping is happening in the main function, the outer loop just checks if pathlist is null or not.

The inner loop is supposed to open the directory and keep sending the 2 parameters to which1, which compares the two strings and returns 1, and 0 if they aren't.

I'm just testing it on ls at the moment, I know I will need to change that string to a variable in my actual program... but what I can't figure out is, why it keeps appending the wrong directory to ls when its printing it.