The Way that can be told of is not the eternal Way;
The name that can be named is not the eternal name.
The Nameless is the origin of Heaven and Earth;
The Named is the mother of all things.
Therefore let there always be non-being,
 *so we may see their subtlety,
And let there always be being,
 *so we may see their outcome.
The two are the same,
But after they are produced,
 *they have different names.

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <wchar.h>
#include <string.h>

#define FALSE 0
#define TRUE 1
#define MAXWORDS 100

#define NullChar '\0'

/*structure of the double linked list*/
struct NODE2 
{
 struct NODE2 *pNext;
 struct NODE2 *pPrev;
 char* nData;
}*pHead, *pTail, *pNode,*pHead2, *pTail2, *pNode2,*pHead3,*pTail3,*pNode3;

struct COUNT
{
 int lineNo; /*line no*/
 int words; /*total word count*/
}file, file2;

/*PROTOTYPES */
void midFunct(char *ch1);
void adddll2(char *ch2);
void addll3(char *ch2);
void display(struct NODE2 *pNode, struct NODE2 *pNode2);
int strcomp(const char *src1,const char *src2);
void blankDiff(char * a , char * b);
int getword(char *word, int lim, FILE * instream);
void check(struct NODE2* pNode2,struct NODE2* pNode3,char *newlinetest);
void display3(struct NODE2 *pNode3);
void removeMe(struct NODE2* pNode3);
    
    
/*man page for mdiff*/
void help()
{
 printf("Usage is: mdiff [option] filespec1 filespec2\n");
 printf("Options:\n");
 printf(" -help\t \n");
 printf(" -b\t \n");
 printf(" -c\t.\n");
 printf(" -i\t \n");
 printf(" -q\t \n");
 printf(" -v No diff\t \n");
 printf("filespec2 can be a drive or directory name.\n");
}



int main(int argc, char **argv)
{
  
 int opt;
 /* options -> the inputs that user has */
 extern int getopt(int argc, char *argv[], char *optionS);
 while ((opt = getopt(argc, argv, "bciqv")) != EOF) 
  {
   switch (opt) 
	{
	case '?':
  printf("Invalid command line option\n");
  help();
  return(1);
	case 'b':
  blankDiff(argv[2], argv[3]);
  break;
	case 'c':
  break;
	case 'i':
  break;
	case 'q':
  break;
	case 'v':
  break;
	}
  }
 return EXIT_SUCCESS;
}



void midFunct(char *ch1)
{
  
 pNode = malloc (sizeof (struct NODE2));
 pNode->nData = ch1;

  
 if (pHead == NULL) {
  pHead = pNode;
  pNode->pPrev = NULL;
 }
 else {
  pTail->pNext = pNode;
  pNode->pPrev = pTail;
 }
 pTail = pNode;
 pNode->pNext = NULL;
}



void adddll2(char *ch2)
{
 pNode2 = malloc (sizeof (struct NODE2));
 pNode2->nData = ch2;
 if (pHead2 == NULL) {
  pHead2 = pNode2;
  pNode2->pPrev = NULL;
 }
 else {
  pTail2->pNext = pNode2;
  pNode2->pPrev = pTail2;
 }
  
 pTail2 = pNode2;
 pNode2->pNext = NULL;


}


void display3(struct NODE2 * pNode3)
{
 pNode3=pHead3;
 while(pNode3)
  {
   printf("%s",pNode3->nData);
   pNode3=pNode3->pNext;
  }
}

/*test stub only*/
/*test function to display link lists*/
void display(struct NODE2 * pNode, struct NODE2 *pNode2)
   /* struct NODE *pNode3)*/
{
 pNode=pHead;
 while(pNode)
  {
   printf("<%s>",pNode->nData);
   pNode=pNode->pNext;
  }
 pNode2=pHead2;
 while(pNode2)
  {
   printf("[%s]",pNode2->nData);
   pNode2=pNode2->pNext;
  }
}

int strcomp ( const char *_src1, const char *_src2 ) 
{
 while ( *_src1 == *_src2++ ) 
  if ( *_src1++ == '\0' ) 
   return 0;
 /* while ( *_src1 == *_src2++ ) */
  
 if ( *_src1 == '\0' )  
  return -1;
  
 if ( *--_src2 == '\0' ) 
  return 1;
  
 return ( ( ( unsigned char ) *_src1 ) - ( ( unsigned char ) *_src2 ) );
}
/* int strcomp ( const char *_src1, const char *_src2 ) */

void adddll3(char *ch3)
{
 pNode3 = malloc (sizeof (struct NODE2));
 pNode3->nData = ch3;
 if (pHead3 == NULL) {
  pHead3 = pNode3;
  pNode3->pPrev = NULL;
 }
 else {
  pTail3->pNext = pNode3;
  pNode3->pPrev = pTail3;
 }
 pTail3 = pNode3;
 pNode3->pNext = NULL;
  
}


/* getword: get next word or character from input */
int getword(char *word, int lim, FILE * instream)
{
 int c;
 char *w = word;
 while ((isspace(c = fgetc(instream))) && (c !='\n'))
  ;
  
 if (c != EOF)
  *w++ = c;
  
 if (!isalpha(c) ) {
  *w = NullChar;
  return c;
 }
  
 for (; --lim > 0; w++)
  if (!isalnum(*w = fgetc(instream))) {
   ungetc(*w,instream);
   break;
  }
  
 *w = NullChar;
 if (c == EOF)
  return EOF;
 return word[0];
}

 
void blankDiff(char* a, char* b)
{
 char *array1;
 char *array2;
 FILE *instream;
 FILE *instream2;
 instream=fopen(a,"r");
 instream2=fopen(b,"r");
 char *c, *d;
  
 if(instream==NULL){
  c=strcpy("\\",a);
  instream=fopen(c,"r");
 }
 if(instream2==NULL){
  d=strcpy("\\",b);
  instream2=fopen(d,"r");
 }
 a=c;
 b=d;

 if((instream == NULL) || (instream2 == NULL))
  {
   printf ("File Open Error!");
   exit(99);
  }
 int d2, k2;
 file.words=file2.words=0;
 file.lineNo=file2.lineNo=0;

 while((d2 != -1) || (k2 != -1))
  {
   array1=malloc(100*sizeof(array1));
   array2=malloc(100*sizeof(array2));
   d2=getword(array1,MAXWORDS,instream);
   k2=getword(array2,MAXWORDS,instream2);
   midFunct(array1);
   adddll2(array2);
   file.words = file.words +1;
   file2.words=file2.words+1;
   if(d2 == '\n' )
	file.lineNo=file.lineNo +1;
   if(k2 == '\n')
	file2.lineNo=file.lineNo +1;
  }
  
 char *array3=malloc(100*sizeof(array3));
  
 char *newlinetest=malloc(100*sizeof(char));
 strcpy(newlinetest,"\n");

 char *spacetest=malloc(100*sizeof(char));
 strcpy(spacetest,"");

 pNode=pHead;
 pNode2=pHead2;
 pNode3=pHead3;

 register int temptest=1;

 while(pNode!=NULL)
  {
   
   while(pNode3!=pHead3){
	if(pNode3 !=NULL){
  pNode3=pNode3->pPrev;
  removeMe(pNode3->pNext);

	}
 
   }
   free(pNode3);
   free(pHead3);
   free(pTail3);
   while(temptest != 0)
	{
  temptest=strcomp(pNode->nData,newlinetest);
  array3=pNode->nData;
  adddll3(array3);
  pNode=pNode->pNext;
 
  if(pNode==NULL)
   break;
	}

   check(pNode2,pNode3,newlinetest);

   temptest=1;
  }

}
void removeMe(struct NODE2* pNode3)
{
 if(pNode3==pHead3)
  {

   return;
  }
  
 if(pNode3->pPrev == NULL)
  pHead3=pNode3->pNext;
 else
  pNode3->pPrev->pNext=pNode3->pNext;

 if(pNode3->pNext == NULL)
  pTail3=pNode3->pPrev;
 else
  pNode3->pNext->pPrev=pNode3->pPrev;
 free(pNode3);
}


void check(struct NODE2* pNode2,struct NODE2 *pNode3,char *newlinetest)
{
 int compare,yes,check2;
 int length;
 yes=0;

 if(file2.lineNo > file.lineNo)
  length=file.lineNo;
 else 
  length=file2.lineNo;
 
  
 pNode3=pHead3;
 pNode2=pHead2;
  


 while(pNode2!=NULL)
  {

   if(strcomp(pNode2->nData, newlinetest)==0)
	check2=0;
	
   if(pNode3 == NULL)
	{
  break;
	}
   
   length--;
   
   if(length==0){
	check2=0;
	break;
   }
   
   compare=strcomp(pNode2->nData,pNode3->nData);

   if(compare !=0){
	(check2)++;
   }
   if((pNode3 !=NULL) && (strcomp(pNode2->nData,newlinetest) ==0))
	{
  while(strcomp(pNode3->nData,newlinetest)!=0)
   pNode3=pNode3->pNext;
	}
   
   if((pNode3==NULL) && (strcomp(pNode2->nData,newlinetest)!=0))
	{
  while(strcomp(pNode2->nData,newlinetest)!=0)
   pNode2=pNode2->pNext;
	}

   if(strcomp(pNode3->nData,newlinetest)==0){
	if(check2==0){
  yes=1;
	}
	pNode3=pHead3;
   }

   pNode2=pNode2->pNext;
   pNode3=pNode3->pNext;
 if(yes==1){
  display3(pNode3);   
  }
  

 }
  
}