Bank like system

Hey,
I am trying to make a system as a class assignment. I have only started but I am unsure of how to do one piece of code already. I have:

Code:

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//Files using CSV Format

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

struct customer
{
        int accno;
        char name[25];
        char address[50];
       
};

typedef struct customer C;

void newperson( C * cArray);
void printperson( C * cArray);

#define CUSTOMERS "customers.txt"

void main()
{       
        C  * cArray;
       
        int numPersons=0;

        cArray = ( C * ) malloc( 1 * sizeof( C ) );
       
        system("COLOR 1E");
       
        newperson(cArray);
        printperson(cArray);
               
        printf("\n\nWritten to file\n\n");
}

void newperson( C * cArray)
{
        char ch;
       
        FILE * customerfile = fopen(CUSTOMERS, "r");

        if (customerfile==NULL)
        exit(errno);
       
                printf("Enter name:\n");
                gets( (cArray )->name);
               
                printf("Enter address:\n");
                gets( (cArray )->address);
               
                printf("\nPress return to write information...\n");
                ch = getchar();
                fclose(customerfile);
}

void printperson( C * cArray)
{

                FILE * customerfile = fopen(CUSTOMERS, "a");
       
                if (customerfile==NULL)
                exit(errno);
               

        printf("Name\t\tAddress");
       
        printf("\n%d", (cArray)->accno);
        printf("\t%s", (cArray)->name);
        printf("\t\t%s", (cArray)->address);

        fprintf(customerfile,"%s,%s\n", cArray[0].name, cArray[0].address);
        fclose(customerfile);
}

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This much is working. What I want to be able to do is set up a counter so that accno will increment itself by 1 each time a new account is written to the file. Anyone any guidance on how to go about this?

Well first you will want to read how many accounts are in the file. A quick and easy way to do this could be to get the number of newlines then divide it by however many lines the data for each account uses.

If there is no one added yet how do i work around this? Should I just hardcode a sample customer to file to overcome this?

After opening the file test if the file pointer is null, if so the file does not exist so set the count to 0. Alternatively if a file exists but is empty then you count will finish at 0.

Agh, you are using void main I see. And gets too!
Void main is undefined and gets is dangerous. Read:
http://cpwiki.sourceforge.net/Gets
and
http://cpwiki.sourceforge.net/Void_main

Try fixing those first.
As for the count, well... you need to keep track of it. So you could write it at the beginning of your file.
When the program runs, read back that number and increase it by one for every new account and write the new number to file.

I'm trying a slightly diff approach now but keep getting an error early on. Help appreciated again

Code:

---

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

struct customer
{
        int accno;
        char name[25];
        char address[50];
       
};

typedef struct customer C;

void loaddata(C * cArray);
void readperson( C * cArray);
void printperson( C * cArray);

#define CUSTOMERS "customer.txt"
#define LINE_LENGTH 80                                        //Maximum buffer size for reading in file.

int main(void)
{
        C  * cArray;
       
        int numPersons=0;
       
        cArray = ( C * ) malloc( 1 * sizeof( C ) );
        loaddata(cArray);
        readperson(cArray);
        printperson(cArray);
               
        printf("\n\nWorking\n\n");
}

void readperson( C * cArray)
{
        char ch;       
               
                printf("Enter name:\n");
                gets( (cArray )->name);
               
                printf("Enter address:\n");
                gets( (cArray )->address);
               
                printf("\nPress any key to continue...\n");
                ch = getchar();
}

void printperson( C * cArray)
{

                FILE * customerfile = fopen(CUSTOMERS, "a");
       
                if (customerfile==NULL)
                exit(errno);
               
        printf("Name\t\tAge");
       
        printf("\n&#37;s", (cArray)->name);
        printf("\t\t%s", (cArray)->address);
       
        fprintf(customerfile,"%s,%s\n", cArray[0].name, cArray[0].address);
        fclose(customerfile);
}

void loaddata(C * cArray)
{       
        FILE * customerfile = fopen(CUSTOMERS, "r");
        char tmpline[LINE_LENGTH];
       
        int linecount=0;                                                                        //Used as counter for number of lines
        int k = 0;       
       
        if (customerfile==NULL)
        exit(errno);
       
            linecount = 0;
        while (fgets(tmpline,LINE_LENGTH,customerfile) != NULL)
                linecount++;
        *cArray = malloc(linecount * sizeof(C));       
        if (cArray==NULL)
                exit(errno);

        rewind(customerfile);

        printf ("Data loaded\n");
}

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Were you not already corrected about gets?
http://cpwiki.sourceforge.net/gets

I was but its working for time being so i want to try get something happening. can rectify gets then. Please help and i promise once i have time to learn new code i will never use gets again!

I think you also failed to mention what is wrong.
Plus changing gets isn't difficult.
fgets(buffer, sizeof(buffer), stdin)
That's all.

So
gets( (cArray )->name);
becomes
fgets(cArray->name, sizeof(cArray->name), stdin);

Code:

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*cArray = malloc(linecount * sizeof(C));

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This is incredibly wrong.
You dereference the actual cArray pointer and store the address to the allocated memory there.
Hmmm. How do you assign void* to customer?

And after that... you aren't even reading the data from the file into the array.
Yet later you're actually asking for new data and put it into your struct, making the whole previous loaddata useless.
And you're just writing one entry at the end of the file, as well.
What are you trying to accomplish?

What i aim to do is that when i start the program it will read in the file of customers and see how many are there. when it has that done i want to add a customer +1 from the last customer but im getting stranded at it!

Add another customer you say... yet what are you going to do with all those? Why do you need to know how many customers there are?

i will hopefully be puttin in a binary search to find customers so need it for that. i will also need to know for when the program is run several times how many customers are already there to increment the account number by 1 for the next customer.

You obviously need to dynamically allocate memory, so you should pass a pointer to pointer to your function to allocate the memory you need and then read the file into that array.
There are two approaches to this. Either you can read through the entire file and count the lines and then fill the array or you can allocate n amount of structs, read n amount of structs and if it isn't enough, reallocate your array to hold more structs and continue reading.

Once you have all of them in your big array, you can do whatever with it.

I want to do the first option where I read the lines.
Is my code pure rubbish thus far so? The whole project I will want to have users who can have one of 3 types of account. They will be able to lodge or withdraw money from these account and get a statement. If I can get the accounts working including the account number i have a fair idea how to do the accounts. (I think)

No, it just needs a little modification, that's all. I don't know if you think you can implement a double pointer system?
The reason is that main also needs access to your dynamic buffer, so you must pass a pointer to that pointer and allocate memory in it.
Give it a try.

I failed miserably at it when I tried... should i just skip users for time being and try work on other aspects of the project?

Code:

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int main()
{
        char* pUsers;
        ReadUsers(&pUsers);
}

void ReasUsers(char** pUsers)
{
        /* ... */
        *pUsers = malloc(...);
}

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A little advice.

Hey again all,
Project fell by the way side after a small incident skiing. 5000ft up, bad slip & trees = !good! Back on my feet sort of again and back to the joys of C... I cant work my previous code propely so im trying a different way. Again all help is both needed and necessary!

I have 1 file called customers.txt
The problem starts when I try include either of the functions:
sort(users,userssize);
userssize=readfromfile(users,linecount);
When I include the sort my file becomes gibberish. When I include the read function it simply crashes.

Regards,
Jer

Code:

---

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

struct person                        //creates a struct called person which holds all personal details
{
        char name[25];
        char address[50];
        int idnum;
};

typedef struct person P;

#define customer "customers.txt"                        //defines various filenames for easy access
#define readwrite "r+w"                                        //defines commands used in fopen()
#define read "r"
#define write "w"

int addusers(P array[],int linecount);                        //function prototypes
void write2file(P array[],int size);
void sort(P array[],int size);
int readfromfile(P array[],int totalusers);



void main ()
{
        int size=10,id=0;                        //creates counters for array sizes and id is used in binary search
       
        int cntrl=0,linecount=0,linecounter2=0,userssize=0;                //creates counters for array sizes
               
        P users[50];        //creates an array of struct type person
       
                do{                                //this do loop controls the main menu, it loops around indefinately until 0 is pressed to exit
        printf("\t\tWelcome to HBC - Higher Bank Charges\n\n");
       
       
        printf("\t1.        Add New Customer\n");
        printf("\t0.        Exit Menu\n\n");
       
        printf("Please Enter Your Choice From The Menu\n");
        scanf("%d",&cntrl);
       
        if(cntrl==1)        //if 1 is pressed it enters the adduser section
        {
                linecount=0;                               
                //userssize=readfromfile(users,linecount);//reads from the file and puts this data into the array
                userssize=addusers(users,userssize);//this adds new users and returns the new size of the array               
                //sort(users,userssize);        //this sorts the array befoe it is written out into a file
                write2file(users,userssize);//writes the contents of the customer array to a file
                               
        }
       
                else if(cntrl!=0)
        {
                printf("Invalid Choice,Please Pick Another Number\n");
               
        }
       
        }while(!cntrl==0);
}


int addusers(P array[],int linecount) //this function adds new users
{

        int x=0;
        int resize;                       
       
        resize=linecount;
       
       
       
                printf("Please enter the user's id number\n");
                scanf("%d",&array[x].idnum);
                getchar();
               
               
                printf("Please enter the customers name\n");
                gets(array[x].name);
               
               
               
                printf("Please enter the customers address\n");
                gets(array[x].address);
               

        printf("esteban cambiasso");
               
        linecount=resize;
       
        return linecount;
               
} 


void write2file(P array[],int size)//writes the contents of the array to a file
{

        int j=0;
        FILE * customerfile = fopen(customer, "a");
       
        if (customerfile==NULL)
        {
                printf("%s cannot be opened\n",customer);
                  exit(errno);
          }
         
          //for(j;j<size;j++)
          //{
          //prints array to file           
         
          fprintf(customerfile,"%d",array[j].idnum);
          fprintf(customerfile,"|%s",array[j].name);
          fprintf(customerfile,"|%s\n",array[j].address);
         
          if(feof(customerfile))//break;
         
          //}
         
          fclose(customerfile);///closes connection
         
 }
 
 int readfromfile(P array[],int totalusers)//reads in customer details from file using string token
{
    char customerdet[100];//created to read in all customer details as one string
        FILE * customers;
        char * strpointer = NULL;
        int tmpint;
        int i = 0;
        customers = fopen(customer, read);  //opens connection to file
       
        if (customer ==NULL)
        {
                printf("%s can not be opened\n",customer);
        exit(errno);
        }

       
        while(!feof(customers))// not at end of file
        {
        fgets(customerdet,100,customers);//reads in details as one string
       
       
        //start strtok
       
        strpointer = strtok( customerdet, "|" );
        sscanf(strpointer,"%d",&tmpint);
        array[totalusers].idnum = tmpint;
       
                while(strpointer != NULL) //as long as pointer doesnt =0 use string token
                {
 
                          strpointer = strtok( NULL, "/" );
         
                  switch(i)
                          {
                                  case 0:
                                  strcpy(array[totalusers].name,strpointer);//copies part of string pointed at by string token to name
                                  break;
                 
                                  case 1:
                         
                                  strcpy(array[totalusers].address,strpointer);//copies part of string pointed at by string token to address
                                  break;
                 
         
                          }
         
          i++;
        }

                  i=0;
                     
     
        totalusers++;
                                                                         
        }
       
        fclose(customers);
        return totalusers;
       
}

 void sort(P array[],int size)//bubble sort used to sort customer array
{

        int k=0;
        int j=0;
        P hold;
       
        //for(k;k<size;k++)
        //{
       
                //for(j;j<(size-1-k);j++)
                //{
                        if(array[j].idnum > array[j+1].idnum)
                        {
                                hold = array[j];
                                array[j]= array[j+1];
                                array[j+1]=hold;
                        }
                //}
               
        //}
       
}

---

while(!feof(customers))
do not use feof to control loop - read FAQ

Code:

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while(strpointer != NULL) //as long as pointer doesnt =0 use string token
                {
 
                          strpointer = strtok( NULL, "/" );

---

what if strtok returns NULL? you still try to copy from NULL pointer...

your customer file is delimitered with | why are you strtoking it with "/"?
what about checking the bounds of the customer array?

When i tried to implement the other efof loop it would not accept the "return(0)" for me? Any idea why this is?

To fix copying the null pointer do i just need to implement some way of pointing it to a new funstion?

i changed the line to "|" - that was an typo
what about checking the bounds of the customer array? - I'm not sure what you mean here, sorry. Could you elaborate a small bit more to a complete c idiot!

Quote:

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Originally Posted by Signpost

Hey again all,
Project fell by the way side after a small incident skiing. 5000ft up, bad slip & trees = !good!

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Yet it seems that your accident has affected your code, as well. You were corrected at least twice before. Do not use void main and do not use gets. It's the devil's tool.
Gets can be the cause of your crashes, too, due to its incredible poor design. Forget that gets ever existed. It should never, ever be used.

Quote:

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Originally Posted by Signpost

When i tried to implement the other efof loop it would not accept the "return(0)" for me? Any idea why this is?

---

That says nothing. If you changed the loop, show the new code.

Quote:

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To fix copying the null pointer do i just need to implement some way of pointing it to a new funstion?

---

You need to not copy the string if strtok returns NULL. You can't copy something that doesn't exist, can you? So check if the result is not NULL before trying to do any copying.

Quote:

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what about checking the bounds of the customer array? - I'm not sure what you mean here, sorry. Could you elaborate a small bit more to a complete c idiot!

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It means that perhaps something is writing beyond the end of the customer array. Do you have Visual Studio? Visual Studio can easily catch buffer overrun errors.
Otherwise you're just going to have to do it manually. There are several methods. One could be to create one extra customer object (+1 to the array) and check if that object changes (it shouldn't!).