Thread: help...

the delete function in the following gives me an error everytime i run the program, but no error's appear when i compile it...

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

struct carData {
int carNum;
char make[15];
char model[15];
int year;
double price;
char regNum[10];
long int mileage;
struct carData *next;
};

typedef struct carData CarData;
typedef CarData *carDataPtr;

void Add();
//void Update();
char Delete(carDataPtr *);
//void List();

int main()
{
int decision;

FILE *in;
//struct carData details = {0, "", "", 0, 0.0, "", 0};
carDataPtr details = NULL;

if((in = fopen("cardetails.", "rb+")) == NULL) {
printf("File <cardetails.dat> cannot be opened.\n");
exit(1);
}
/*for(i=1;i<=100;i++)
fwrite(&details, sizeof(struct carData), 1, in);
fclose(in);*/

printf("** Al Hayes Motors Processing System **\n\n");
printf("Choose an option:");

do {
printf("\n1. Add a new record.\n");
printf("2. Update a record.\n");
printf("3. Delete a record\n");
printf("4. List all records on a formatted file for printing\n");
printf("5. Exit\n>> ");
scanf("%d", &decision);

switch(decision) {
case 1:
Add();
break;
/*case 2:
Update();
break;*/
case 3:
Delete(&details);
break;
/*case 4:
List();
break;*/
default:
if(decision!=5) {
printf("Invalid option - Choose Again!\n\n");
}
}

}
while(decision != 5);

printf("Goodbye!\n");

return 0;

}

void Add()
{
char ans;
FILE *in;
struct carData details = {0, "", "", 0, 0.0, "", 0};

if((in = fopen("cardetails.dat", "rb+")) == NULL)
printf("File <cardetails.dat> cannot be opened.\n");
else {
printf("Enter Car Number<1-100; 0 - back to main screen>: ");
scanf("%d", &details.carNum);

while(details.carNum != 0) {

fflush(stdin);
printf("Enter Make: ");
scanf("%s", details.make);
printf("Enter Model: ");
scanf("%s", details.model);
printf("Enter Year: ");
scanf("%d", &details.year);
printf("Enter Price: ");
scanf("%lf", &details.price);
printf("Enter Reg Num: ");
scanf("%s", details.regNum);
printf("Enter Mileage: ");
scanf("%ld", &details.mileage);
printf("Would you like to write this data<y/n>");
scanf("%c", &ans);
scanf("%c", &ans);
if(ans=='y') {
fseek(in, (details.carNum - 1) * sizeof(struct carData), SEEK_SET);
fwrite(&details, sizeof(struct carData), 1, in);
printf("File written succesfully\n\n");
}
printf("Enter Car Number<1-100; 0 - back to main screen>: ");
scanf("%d", &details.carNum);
}

fclose(in);

}

}

char Delete(carDataPtr *sPtr)
{
char delNum;
carDataPtr prev, curr, temp;

printf("Enter Car Number to delete<1-100>: ");
scanf("%c", &delNum);

if(delNum == (*sPtr)->carNum) {
temp = *sPtr;
*sPtr = (*sPtr)->next;
free(temp);
printf("Car Number %c has been deleted\n", delNum);
}
else {
prev = *sPtr;
curr = (*sPtr)->next;

while(curr != NULL && curr->carNum != delNum) {
prev = curr;
curr = curr->next;
}

if(curr != NULL) {
temp = curr;
prev->next = curr->next;
free(temp);
printf("Car Number %c has been deleted\n", delNum);
}
}

return '\0';

}

Dear Unregistered Guest

Please can you supply the dat file that this program access.

I have compiled using Borland's C++ V 3 DOS and got a warning about 'in' being assigned a value that is never used.

When I run the programme it aborts at the file open stage because I do not have the file.

FILE *in;
//struct carData details = {0, "", "", 0, 0.0, "", 0};
carDataPtr details = NULL;

if((in = fopen("cardetails.", "rb+")) == NULL)
{
printf("File <cardetails.dat> cannot be opened.\n");
exit(1);
}

Have you managed to open the file using the code supplied ?

Wait to hear

Stephanos

([email protected])