Same Questiion But I Do Not Know How To Do It In Linked List.

**nefsan** · 10-06-2007

A parts company has information on its parts in a data file "parts.dat". The data in the data file is structured as follows:

The data file consists of 2 parts. The first part has information on the parts. Each line of data contains the part number ( an integer), a description of the part, the quantity in stock and the unit price separated by one or more spaces. The description of the part is contained within two '*' ( the asterisks are not part of the description). This section of data is terminated by a line with a single 0.

The next half of the data file consists of transactions performed on the data. Each line consists of two letters indicating the transaction to be performed and this is followed by data relevant for the transaction. The different kinds of transactions are as follows:

1. To add a new part:

ap partNumber *description* quantityInStock unitPrice

2. To sell a part:

sp partNumber quantitySold

3. To change the price of a part:

cp partNumber newPrice

4. To add stock of a particular part:

cq partNumber quantityToAdd

5. To list all information on all parts:

ls

YOUR PROGRAM MUST USE A LINKED STRUCTURE THAT MAINTAINS THE LIST IN SORTED ORDER BY PART NUMBER .
YOUR PROGRAM MUST CATER FOR CASES WHERE THERE IS NOT ENOUGH QUANTITY IN STOCK FOR A SALE ,OR THE PART NUMBER DOES NOT EXIST .IN THESE CASES ,APPROPRIATE ERROR MESSAGES MUST BE PRINTED

YOUR PROGRAM MUST ALSO PRINT AFTER PROCESSING ALL THE TRANSACTIONS THE TOTAL SALES FIGURE

An example of the format of the data file is given below.
.

2345 *Stanley Bearing* 178 12.56

3456 *Silver Rims* 4 500.00

7862 *Castrol GTX 50 Body Engine Oil* 29 20

0

ap 9872 *BrakeShoes* 50 2241.00

ls

sp 2345 58

sp 7862 15

cq 2345 100

cp 7862 19.59

ls

I GOT ALOT OF TROUBLE WITH STRUCTURES JUST A WEEK AGO NOW HOW THE HECK DO I DO THIS ONE?IS IT POSSIBLE TO MODIFY MY STRUCTURE PROGRAM TO A LKINK LIST ONE? HELP

**dwks** · 10-06-2007

Here's the other thread in question: http://cboard.cprogramming.com/showthread.php?t=94162

It seems that you already know how to solve the problem, at least in one way. So perhaps you just need some basic information about linked lists? If so, why not try http://www.google.ca/search?hl=en&q=...e+Search&meta=

**Bokarinho** · 10-06-2007

Originally Posted by nefsan

IS IT POSSIBLE TO MODIFY MY STRUCTURE PROGRAM TO A LKINK LIST ONE? HELP

Try asking ADIDAS, they say that impossible is nothing......

**dwks** · 10-06-2007

ADIDAS? You mean sportswear?

IS IT POSSIBLE TO MODIFY MY STRUCTURE PROGRAM TO A LKINK LIST ONE? HELP

Sure, rather than using part[i++], just add a call to add_part_to_linked_list(). But you need to know how linked lists work first . . .

Have you tried anything?

**Bokarinho** · 10-06-2007

Though i would like to give you a hand, watch my code which is not complete, you may get some ideas about how to save things in a array of structs, later we discuss about linked lists.
Well this not complete function tries to read from file the data and store them in an array of structs, also it returns the array or NULL if error exists.

Code:

#define BUFFER_SIZE 1024
#define OFFSET 3


typedef struct p_struct
{
	int partNumber;
	char description[128];
	int quantityStock;
	float unitPrice;
}PartStruct;


PartStruct* ReadFromFile(const char *filename)
{
	if(filename == NULL)
		return NULL;
	else
	{
		FILE *file = fopen(filename , "r");
		if(file == NULL)
		{
			fprintf(stderr, "Error in opening '&#37;s' file.\n", filename);
			return NULL;
		}
		else
		{
			//Index.
			int i = 0;
			int j = 0;
			static int error = 0;
			//Strtok pointer.
			char *ptrTok = NULL;
			//Array to hold the data from file.
			char buffer[BUFFER_SIZE];
			//Our array of structs.
			PartStruct *ptrParts = NULL;
			//Get init space.
			ptrParts = calloc(1, sizeof(PartStruct));
			if(ptrParts == NULL)
				return NULL;
			//Initialise buffer.
			memset(buffer, 0 , BUFFER_SIZE);
			while(1)
			{
				if(fgets(buffer, sizeof(buffer), file) == NULL)
					break;
				if(buffer[0] == '\n')
					continue;
				if(buffer[0] == '0')
					break;
				if(buffer[strlen(buffer)-1] == '\n')
					buffer[strlen(buffer)-1] = '\0';
				//Tokens.
				ptrTok = strtok(buffer, " *");
				if(ptrTok == NULL)
				{
					error = 1;
					break;
				}
				else
				{
					if(sscanf(ptrTok,"%d",&ptrParts[i].partNumber) != 1)
					{
						error = 2;
						break;
					}
					while(ptrTok != NULL && j < OFFSET)
					{
						ptrTok = strtok(NULL, " *");
						switch(j)
						{
							case 0:
							case 1:
							case 2:

							default:
							//Error.
						}
						//Advance j.
						j++;
					}
				}
				//Should realloc here.
				i++;
				ptrParts = realloc(ptrParts, (i+1) * sizeof(PartStruct));
			}
			//Close file.
			fclose(file);
			//Return the struct.
			if(!error)
				return ptrParts;
			else
			{
				free(ptrParts);
				return NULL;
		                }
		}
	}
}

**dwks** · 10-06-2007

Code:

PartStruct* ReadFromFile(const char *filename)
{
	if(filename == NULL)
		return NULL;
	else
	{
		FILE *file = fopen(filename , "r");
		if(file == NULL)
		{
			fprintf(stderr, "Error in opening '&#37;s' file.\n", filename);
			return NULL;
		}
		else
		{
		/* ... */

Those elses are useless, and add extra levels of indentation to the rest of the code, which should probably be avoided if possible.

Code:

			ptrParts = calloc(1, sizeof(PartStruct));
			if(ptrParts == NULL)
				return NULL;

What about closing the file?

**Bokarinho** · 10-07-2007

Originally Posted by dwks

Code:

PartStruct* ReadFromFile(const char *filename)
{
	if(filename == NULL)
		return NULL;
	else
	{
		FILE *file = fopen(filename , "r");
		if(file == NULL)
		{
			fprintf(stderr, "Error in opening '%s' file.\n", filename);
			return NULL;
		}
		else
		{
		/* ... */

Those elses are useless, and add extra levels of indentation to the rest of the code, which should probably be avoided if possible.

Code:

			ptrParts = calloc(1, sizeof(PartStruct));
			if(ptrParts == NULL)
				return NULL;

What about closing the file?

Yes you are right, of course i ment adidas sportwear, with messi they say impossible is nothing,the else statements i use are correct they help me in writing my code and organise it in my brain better, i agree they may are not the best choice but there is no fault with it. Am i right?

**dwks** · 10-07-2007

No, no, if you like the else statements then that's fine too. They're just redundant, and like I said involve more indentation.

**Bokarinho** · 10-07-2007

How to read the data from file into your structure, its a complicated way using fgets() and strings, someone else could happily use fscanf() but i just wanted to get some practise with tokens. Well thats the prog:

Code:

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

#define BUFFER_SIZE 1024
#define OFFSET 3

typedef struct p_struct
{
	int partNumber;
	char description[128];
	int quantityStock;
	float unitPrice;
}PartStruct;

PartStruct* ReadFromFile(const char *filename, int *ptrPartSize)
{
	if(filename == NULL)
		return NULL;
	else
	{
		FILE *file = fopen(filename , "r");
		if(file == NULL)
		{
			fprintf(stderr, "Error in opening '%s' file.\n", filename);
			return NULL;
		}
		else
		{
			//Index.
			int i = 0;
			int j = 0;
			static int error = 0;
			//Strtok pointer.
			char *ptrTok = NULL;
			//Array to hold the data from file.
			char buffer[BUFFER_SIZE];
			//Our array of structs.
			PartStruct *ptrParts = NULL;
			//Get init space.
			ptrParts = calloc(1, sizeof(PartStruct));
			if(ptrParts == NULL)
				return NULL;
			//Initialise buffer.
			memset(buffer, 0 , BUFFER_SIZE);
			while(1)
			{
				if(fgets(buffer, sizeof(buffer), file) == NULL)
					break;
				if(buffer[0] == '\n')
					continue;
				if(buffer[0] == '0')
					break;
				if(buffer[strlen(buffer)-1] == '\n')
					buffer[strlen(buffer)-1] = '\0';
				//Tokens.
				ptrTok = strtok(buffer, " *");
				if(ptrTok == NULL)
				{
					error = 1;
					break;
				}
				else
				{
					if(sscanf(ptrTok,"%d",&ptrParts[i].partNumber) != 1)
					{
						error = 2;
						break;
					}
					while(ptrTok != NULL && j < OFFSET)
					{
						ptrTok = strtok(NULL, " *");
						switch(j)
						{
							case 0:
									//Its a bit strange to use this technique only knowing the way the
									//data stored in the file. <fscanf may become a better solution.>
									strcpy(&ptrParts[i].description, ptrTok);
									ptrTok = strtok(NULL, "*");
									ptrParts[i].description[strlen(ptrParts[i].description)] = ' ';
									strcat(&ptrParts[i].description, ptrTok);
								break;
							case 1:
								sscanf(ptrTok,"%d",&ptrParts[i].quantityStock);
								break;
							case 2:
								sscanf(ptrTok,"%f",&ptrParts[i].unitPrice);
								break;
							default:
								printf("Error.\n");
								error = 3;
								break;
						}
						//Advance j.
						j++;
					}
				}
				//Should realloc here.
				i++;
				ptrParts = realloc(ptrParts, (i+1) * sizeof(PartStruct));
				//Remember to get j to zero.
				j = 0;
			}
			//Close file.
			fclose(file);
			//Return the struct.
			if(!error)
			{
				*ptrPartSize = i;
				return ptrParts;
			}
			else
			{
				free(ptrParts);
				return NULL;
            }
		}
	}
}
int main(int argc, char* argv[])
{
	int i;
	int r_size = 0;
	PartStruct *r = ReadFromFile("parts.txt", &r_size);
	for(i = 0; i < r_size; i++)
		printf("%d %s %d %f\n", r[i].partNumber, r[i].description, r[i].quantityStock, r[i].unitPrice);
	free(r);
	printf("Hit any key to exit........");
	getch();
	return 0;
}

**dwks** · 10-07-2007

conio.h . . . last time I looked that had "died with the dinosaurs", as Salem once said . . .

Code:

				i++;
				ptrParts = realloc(ptrParts, (i+1) * sizeof(PartStruct));

I didn't really look at it, but I think that you're allocating one too many elements there. Usually the statements go the other way around.

**nefsan** · 10-10-2007

Code:

 10-07-2007, 03:42 AM    #9  
Bokarinho 
Registered User
 

Join Date: Jun 2007
Posts: 47  How to read the data from file into your structure, its a complicated way using fgets() and strings, someone else could happily use fscanf() but i just wanted to get some practise with tokens. Well thats the prog:


Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>

#define BUFFER_SIZE 1024
#define OFFSET 3

typedef struct p_struct
{
	int partNumber;
	char description[128];
	int quantityStock;
	float unitPrice;
}PartStruct;

PartStruct* ReadFromFile(const char *filename, int *ptrPartSize)
{
	if(filename == NULL)
		return NULL;
	else
	{
		FILE *file = fopen(filename , "r");
		if(file == NULL)
		{
			fprintf(stderr, "Error in opening '%s' file.\n", filename);
			return NULL;
		}
		else
		{
			//Index.
			int i = 0;
			int j = 0;
			static int error = 0;
			//Strtok pointer.
			char *ptrTok = NULL;
			//Array to hold the data from file.
			char buffer[BUFFER_SIZE];
			//Our array of structs.
			PartStruct *ptrParts = NULL;
			//Get init space.
			ptrParts = calloc(1, sizeof(PartStruct));
			if(ptrParts == NULL)
				return NULL;
			//Initialise buffer.
			memset(buffer, 0 , BUFFER_SIZE);
			while(1)
			{
				if(fgets(buffer, sizeof(buffer), file) == NULL)
					break;
				if(buffer[0] == '\n')
					continue;
				if(buffer[0] == '0')
					break;
				if(buffer[strlen(buffer)-1] == '\n')
					buffer[strlen(buffer)-1] = '\0';
				//Tokens.
				ptrTok = strtok(buffer, " *");
				if(ptrTok == NULL)
				{
					error = 1;
					break;
				}
				else
				{
					if(sscanf(ptrTok,"%d",&ptrParts[i].partNumber) != 1)
					{
						error = 2;
						break;
					}
					while(ptrTok != NULL && j < OFFSET)
					{
						ptrTok = strtok(NULL, " *");
						switch(j)
						{
							case 0:
									//Its a bit strange to use this technique only knowing the way the
									//data stored in the file. <fscanf may become a better solution.>
									strcpy(&ptrParts[i].description, ptrTok);
									ptrTok = strtok(NULL, "*");
									ptrParts[i].description[strlen(ptrParts[i].description)] = ' ';
									strcat(&ptrParts[i].description, ptrTok);
								break;
							case 1:
								sscanf(ptrTok,"%d",&ptrParts[i].quantityStock);
								break;
							case 2:
								sscanf(ptrTok,"%f",&ptrParts[i].unitPrice);
								break;
							default:
								printf("Error.\n");
								error = 3;
								break;
						}
						//Advance j.
						j++;
					}
				}
				//Should realloc here.
				i++;
				ptrParts = realloc(ptrParts, (i+1) * sizeof(PartStruct));
				//Remember to get j to zero.
				j = 0;
			}
			//Close file.
			fclose(file);
			//Return the struct.
			if(!error)
			{
				*ptrPartSize = i;
				return ptrParts;
			}
			else
			{
				free(ptrParts);
				return NULL;
            }
		}
	}
}
int main(int argc, char* argv[])
{
	int i;
	int r_size = 0;
	PartStruct *r = ReadFromFile("parts.txt", &r_size);
	for(i = 0; i < r_size; i++)
		printf("%d %s %d %f\n", r[i].partNumber, r[i].description, r[i].quantityStock, r[i].unitPrice);
	free(r);
	printf("Hit any key to exit........");
	getch();
	return 0;
}

is that linked lists??i thought u needed stuff like "last->next" etc.can someone modify this proogram to use linked list instead ?

Code:

////RAJIV RAMKHALAWAN
//ID:806001754
//ASSIGNMENT 1







#include <stdio.h>

typedef struct
{
   int partnum;
   char desc[50];
   int qtyInStock;
   double unitPrice;
} part_info;

#define MAX 50
part_info part[MAX];

int main()
{
    void readDesc(FILE * in, char data[]);
    void AddInOrder(int i);
    
    FILE * in = fopen("parts.dat","r");
    
    if (in == NULL)
    {
        printf("File not found: parts.dat\n");
        system("pause");
        return 1;
    }
    
    
    
    int id, i=0, finished=0;
    double TotalSales=0;
    char trans[3];
    fscanf(in,"%d",&id);
    
    while (id != 0 && i<MAX)
    {
          part[i].partnum = id;
          readDesc(in, part[i].desc);
          fscanf(in,"%d",&part[i].qtyInStock);
          fscanf(in,"%lf",&part[i].unitPrice); 
          if (i>0) AddInOrder(i);         
          i++;
          fscanf(in,"%d",&id);
    }
    
    while (finished==0)
    {
        char ch=getc(in);
        while (ch== ' ') 
              ch=getc(in);
              
        trans[0]=getc(in);
        
        if (trans[0] != EOF) 
        {
           trans[1]=getc(in);
           trans[2]='\0';
                      
           if (strcmp(trans,"ls")==0)
           {
              printf("\nPart No.\tDescription\t\tQuantity in Stock\tPrice\n\n");
              int j;
              for (j=0; j<i; j++)
              printf("%d\t\t%-30s\t%d\t\t%5.2lf\n",part[j].partnum, part[j].desc, part[j].qtyInStock, part[j].unitPrice);
              
           }
           else
           if (strcmp(trans,"sp")==0)
           {
              int j, pnum, qsold;
              fscanf(in,"%d",&pnum);
              fscanf(in,"%d",&qsold);
              for (j=0; j<i; j++)
              {
                  if (part[j].partnum > pnum)
                  {
                     printf("\nPart Number not found: %d!!!\n",pnum);
                     break;
                  }
                  else
                  if (part[j].partnum == pnum)
                  {
                     if (part[j].qtyInStock < qsold)
                     {
                        printf("\nNot enough quantity in stock!!!\n");
                        break;
                     }
                     else
                     {
                         part[j].qtyInStock-=qsold;
                         TotalSales+= (part[j].unitPrice * qsold);
                         break;
                     }
                  }
              }              
           }
           else
           if (strcmp(trans,"ap")==0)
           {
                  fscanf(in,"%d",&part[i].partnum);
                  readDesc(in, part[i].desc);
                  fscanf(in,"%d",&part[i].qtyInStock);
                  fscanf(in,"%lf",&part[i].unitPrice); 
                  if (i>0) AddInOrder(i);         
                  i++;
                  
           }
           else
           if (strcmp(trans,"cp")==0)
           {
              int j, pnum, nprc;
              fscanf(in,"%d",&pnum);
              fscanf(in,"%d",&nprc);
              for (j=0; j<i; j++)
              {
                  if (part[j].partnum > pnum)
                  {
                     printf("\nPart Number not found: %d....\n",pnum);
                     break;
                  }
                  else
                  if (part[j].partnum == pnum)
                  {                     
                         part[j].unitPrice=nprc;                         
                         break;                   
                  }
              }              
           }
           else
           if (strcmp(trans,"cq")==0)
           {
              int j, pnum, qty;
              fscanf(in,"%d",&pnum);
              fscanf(in,"%d",&qty);
              for (j=0; j<i; j++)
              {
                  if (part[j].partnum > pnum)
                  {
                     printf("\nPart Number not found: %d....\n",pnum);
                     break;
                  }
                  else
                  if (part[j].partnum == pnum)
                  {                     
                         part[j].qtyInStock+=qty;                        
                         break;                   
                  }
              }              
           }
           
        } 
        else
           finished=1;
    }
    
    printf("\nTotal Sales: %5.2lf\n",TotalSales);
    
    getchar();
    return 0;
}
/////////////////////////////..........................FUNCTION TO SORT
void AddInOrder(int i)
{
     int j=i;
     part_info temp;
     
     while (j>=0 && (part[i].partnum < part[j-1].partnum))
     {
           temp=part[j];
           part[j] = part[j-1];
           part[j-1] = temp;
           j--;
     }     
}
///////////////////////////..............................FUNCTION TO READ FILE
void readDesc(FILE * in, char data[])
{
     char c;
     int i=0;
     
     c=getc(in);     
     while (c != '*') c=getc(in);
     
     c=getc(in);
     data[i]=c;
     
     c=getc(in);
     while (c != '*') 
     {
           i++;
           data[i]=c;
           c=getc(in);
     }
     i++;
     data[i]='\0';     
}

**matsp** · 10-10-2007

I don't see any linked list in there - which bit do YOU think does a linked list.

--
Mats

**nefsan** · 10-10-2007

well i think that i need to read the numbers and sort it and then enter it into the linked list.but im not sure how to read and sort the entire string into the linked list. this is my function code for sorting and adding to the end of the list.i can sort and insert using just interges that i enter but i cant read and sort the string into the list.any thoughts on how to do it?

Code:

typedef struct node{
int num;
struct node*next;
}Node, *Nodeptr;
..................................//function to ad in place

Nodeptr makenode(int n){
Nodeptr np=(Nodeptr) malloc (sizeof(Node));
np->num=n;
np->next=NULL;
return np;}

Nodeptr addinplace(Nodeptr top, int n){
np=makenode(n);
prev=NULL;
curr=top;
while(curr!=NULL && n>curr->num){
prev=curr;
curr=curr->next;
}
if(prev==NULL){
                        np->next=top;
return np;}
np->next=curr;
prev->next=np;
return top;
}

**dwks** · 10-10-2007

Use better indentation, for one thing.

i can sort and insert using just interges that i enter but i cant read and sort the string into the list.any thoughts on how to do it?

If you can do it with ints, you can do it with strings. You just have to use functions from <string.h> like strcpy() and strcmp().

**matsp** · 10-10-2007

So, assuming your current method for reading data works OK (I can't tell if it does or not by just looking at the code, but I presume you have tested it??)

So you already have a way to read the line into a part_info, correct?

Now, all you need to do is change the way that you store the part_info from an array into a linked list.

There are two ways to do this: You can either add a the link into your part_info struct, or define a second struct, which has a link and a part_info component - here we get a further choice of either containing the part_info directly in the struct, or using a pointer to it.

I would suggest that the least intrusion is by just adding a link (called "next") into your part_info structure.

Then as you read the data, insert it (at the right place?) into the linked list, and modify your code that searches the array to search the list instead.

May I also suggest that you create a function to search for an item, instead of duplicating code to find a part number several times in your code. [It woudl have been far easier to change your code if you had done that in the first place, as that would have meant that you wouldn't have to change very much at all].

--
Mats

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