Deleting an element from an array of structures - c

Question

I am tasked to create an inventory management program where a user can add an item, edit an item, or delete an item. I am almost done with the code, I am just having a problem in deleting an item, particularly deleting an element from an array of structures.
I already looked for similar problems and tried the solutions suggested. The method I tried in my code was deleting an element in an array by shifting the elements next to it down by 1. The program runs and hypothetically the code should work but every time I run the program and enter the "delete an item" option, the program stops (it doesn't just exit, it says "the program stopped working" meaning I broke a rule or something). I am thinking I might be exceeding the array size or something but I can't point what exactly the problem is. Is it forbidden to shift the elements in an array of structure, or is it just my code? Please help.
This is the code for my structure.
struct details {
char name[30];
double price;
int code;
int qty;
};
details item[SIZE];
This is the main function:
int main (){
int choice; //gets the choice of user from the menu
bool condition = 1; //loops the menu
int count=0; //counts the number of items in the inventory
do{
printheader(); //prints the title of the program
printmenu(); //prints the menu (list of commands)
scanf("%d", &choice);
switch(choice){
case 1: system("cls");
AddItem(count); //function in adding record
count++; //increments every time a new item is added
system("PAUSE");
system("cls");
break;
case 2: system("cls");
EditItem(count); //function in editing a record
system("PAUSE");
system("cls");
break;
case 3: system("cls");
count = DeleteItem(count); //function in deleting a record
system("PAUSE");
system("cls");
break;
case 4: system("cls");
//ViewItem(); //function in viewing a record
system("PAUSE");
system("cls");
break;
case 5: system("cls");
DisplayInventory(count); //function in displaying inventory
system("PAUSE");
system("cls");
break;
case 6: system("cls");
SaveFile(count); //function in saving the records to a file
system("PAUSE");
system("cls");
break;
case 7: system("cls");
count = LoadFile(); //function in loading the records from a saved file
system("PAUSE");
system("cls");
break;
case 8: printf("\nThank you!");
exit(0); //ends the program
break;
default: printf("\nInvalid Input!\n");
getch();
system("cls");
}
}while(condition = 1);
return 0;
}
This is the DeleteItem() function. It accepts n which is the number of items/records.
int DeleteItem (int n){
printheader();
int i=0, code, pos;
bool cont = true;
printf("\nEnter the code of the item you want to delete: ");
scanf("%d", code);
do{
if(code==item[i].code){
for (pos=i; pos<(n-1); pos++){
// item[pos].name = item[pos+1].name; //this basically deletes the i'th element and shifts the remaining ones
item[pos].price = item[pos+1].price;
item[pos].code = item[pos+1].code;
item[pos].qty = item[pos+1].qty;
}
printf("\nItem deleted!");
cont = false; //loop ends once the input of the user matches the data in the inventory
}
if(i==n){
printf("\nCode not found!\n\n");
cont = false; //loop ends when there are no matches
}
i++;
}while(cont);
}
When the delete an item option is entered in the program, the program asks the user for the code of the item. The program then scans the array of structures for an an element (item[i].code) that matches the code. Ideally, the program should delete the element and shift the other elements if the code matches. However, what happens is the program crashes and stops. I need help to spot where the problem is. Thank you very much!
EDIT
DeleteItem function:
int DeleteItem (int n){
printheader();
int i=0, code, pos;
//bool cont = true;
printf("\nEnter the code of the item you want to delete: ");
scanf("%d", code);
while(i<n){
if(code==item[i].code){
for (pos=i; pos<(n-1); pos++){
item[pos] = item[pos+1];
}
printf("\nItem deleted!");
break;; //loop ends once the input of the user matches the data in the inventory
}
i++;
if(i==(n-1)){
printf("\nCode not found!\n\n");
break;; //loop ends when there are no matches
}
}
return (n-1);
}
I'm a total newbie with C so I'm really sorry if you see some problematic codes. I'm working on it.

Answer 1

One problem is that your check for i == n is done after you have indexed the array using i. To fix that you should increment i before the check. Like:
i++; // Increment first
if(i==n){ // then check
printf("\nCode not found!\n\n");
cont = false; //loop ends when there are no matches
}
Another problem is that you don't handle the case where n is zero. In general I think that a while(i < n) { ... }; is a better approach than a do { ...} while(...);.
Also notice this code (currently commented out) is wrong:
// item[pos].name = item[pos+1].name;
You can't copy a string using assignment (i.e. =). You'll need to use strcpy
Also I can't see any update of count when an item is deleted. I guess that's bug... I would assume that count has to be decremented.
Finally, I don't see the function returning any value. That's also a bug since you define the function to return an int.
A note...
Using a flag like cont to terminate the while loop will work fine and is therefore not a bug. However, you don't really need a flag. You could do using either a break like:
do{
...
...
if(i==n){
printf("\nCode not found!\n\n");
break; //loop ends when there are no matches
}
i++;
}while(1);
or simply do a return as the function has nothing more to do.
EDIT
OP has posted a second revision of the code. This edit address that second revision.
One problem with the second revision is that the code always return n-1. That is done even when the "code" wasn't found. That's a bug.
The if(i==(n-1)){ is also wrong as it means item number n-i will never be tested.
Try something like this instead:
int DeleteItem (int n){
printheader();
int i=0, code, pos;
printf("\nEnter the code of the item you want to delete: ");
scanf("%d", code);
while(i<n){
if(code==item[i].code){
for (pos=i; pos<(n-1); pos++){
item[pos] = item[pos+1];
}
printf("\nItem deleted!");
return n-1; // End the function and return n-1 as an item was deleted
}
i++;
}
printf("\nCode not found!\n\n");
return n; // End the function and return n as no item was deleted
}
BTW: You should always check the value returned by scanf