Thread: Nested Structs

Hey Guys I'm having some problems with this code

Code:

#include <stdio.h>
#include<string.h>

FILE  *in_fptr,   /* Input File Pointer; points to the file 
                     containing the input to the program */
      *out_fptr,  /* Output File Pointer; points to the file to 
                     contain all the output of the program */
      *fopen();

#define  TRUE          1
#define  FALSE         0
#define  NAME_LENGTH   10  /* maximum number of characters in name */
#define  COM_LENGTH    3   /* number of characters in a command    */
#define  HT_SIZE       59  /* number of entries in the hash table  */
#define  STEP_SIZE     29  /* value to be added to the hash value 
                              for resolving hash collisions        */

/* an entry in reference queue */
struct  rq_entry {
     int     lineno;
     struct  rq_entry  *next;
};

/* an entry in hash table */
struct  ht_entry {
     char    ht_name[NAME_LENGTH + 1];
     struct  rq_entry  *front;  /* a queue is used to keep track of */
     struct  rq_entry  *rear;   /* references to a name*/
};
struct  ht_entry  hash_tbl[HT_SIZE];  /* hash table */

void init();
void search();
int hash();
void tbl_flush();


/********************************************************************/

main()
{
   char command[COM_LENGTH + 1],   /* the command in the input */
        inp_name[NAME_LENGTH + 1]; /* the name in the input    */
	int line = 1;//keep track of line in input file, for reference queue.
	int name_status;//either represents a duplicate entry or undefined
						 //name.
	int *found;//store value passed by search routine.
	
		init();
		
		fprintf(out_fptr,"\tInput Data\n%+2Command %+5Name\n");
		while(fscanf(in_fptr, "%s%s", command, inp_name)!=EOF){
			line++;//next line in program.
				if(strcmp(command, "DEF")==0){//if define is command.
													//name needs to be inserted, or
											   	//a duplicate reference note needs to
											   	//be placed.
					fprintf(out_fptr,"%+5s\t\t");
					name_status=hash(inp_name, TRUE);//passes name and flag telling hash routine
																//to not only hash the name, but try to insert
																//as well.
					if(name_status==FALSE){//name status set to false, when name was already
											  //defined.
						fprintf(out_fptr,"%s\t\t***Duplicate Name***\n", inp_name);
						name_status=TRUE;//reset name_status for next name/symbol.
											  
						}//end if.
					else//name has only been defined once.
						fprintf(out_fptr,"%s\n", inp_name);
					
						}//end else.
			else if(strcmp(command, "USE")==0){
				fprintf(out_fptr,"%5s\t\t", command);
				search(inp_name, &found);//name is being used, need to
								  	  //check if it exists first.
				
				if(found==FALSE)
					fprintf(out_fptr,"%s\t\t***Undefined Name***\n", inp_name);
				else
				    
					fprintf(out_fptr,"%s\n", inp_name);
				}//end else if.
			else{
				printf("Invalid command...closing.\n");
				return 0;
				}//end else.
			 }//end while.
	
	//tbl_flush);//output the resulting data structure to the output
					 //file.
					 
	
	printf("BYE!\n");
	system("PAUSE");	

}/* end of main */

/*******************************************************************/

void init()
{	 
	
	int i;
	in_fptr=fopen("lab1.in", "r");
	out_fptr=fopen("lab1.out", "w");
	for(i=0; i<HT_SIZE; i++){
		hash_tbl[i].front=NULL;//initialize each index's queue to empty.
		hash_tbl[i].rear = NULL;
	    strcpy(hash_tbl[i].ht_name, "0");//initialize names in index
												   //of hash table to empty.
		}

 }/* end of init */

/********************************************************************/

void search(name_ptr, found_ptr, ind_ptr)

   char *name_ptr;   /* name to be searched */
   int *found_ptr;  /* flag to indicate whether or not the name being
                       searched for is in hash table */
   int *ind_ptr;    /* index into the hash table */
	
	
{
	*ind_ptr=hash(name_ptr, FALSE);//set index pointer to index generated by
											 //hash function.
	 							
	while(strcmp(hash_tbl[*ind_ptr].ht_name, "0")!=0){//while index is
																	  //not empty.
        if(strcmp(hash_tbl[*ind_ptr].ht_name, name_ptr)==0){//if name found.
            *found_ptr=TRUE;
        if(hash_tbl[*ind_ptr].front == NULL){
            hash_tbl[*ind_ptr].front -> lineno = 5; 
            
              
        }         
			return;
			}
		else{//an empty index was found, where name should have been.
			*ind_ptr=*ind_ptr+STEP_SIZE;
			if(*ind_ptr>HT_SIZE)
				*ind_ptr=*ind_ptr%HT_SIZE;
				}
		}
	
	*found_ptr=FALSE;//name not found.

it all compiles just fine but the line hash_tbl[*ind_ptr].front -> lineno = 5; makes it crash at run time and I don't know why, I need to access the lineno variable so I can add things to the queue...any help would be appreciated