How to pass array of structure as a parameter of int function

I would like to pass array of structure as a parameter of int function but every time I try to do it. I get the [Error] expected ';', ',' or ')' before '.' token on line 19 where the int function name add is. If I change to int add(int totalCost,struct items *input,int quantity) there will be [Warning] passing argument 2 of 'add' makes pointer from integer without a cast.

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

struct items
{
    int No;
    char singleitem[29];
    int cost;
};

struct items input[5] = { {0, "Aluminium-air battery",355}, { 1, "Bunsen cell",500}, { 2, "Dry cell",550 }, { 3,"Galvanic cell",350},
};
struct items* ptr = input;

int main()
{
    int nonRechargeableBatteries,i=0,choice,c=1,a[10],totalCost=0,quantity=0;

int add(int totalCost,struct items input[i].cost,int quantity)
{
    totalCost+=input[i].cost*quantity;
    return totalCost;
}

    for(i=0; i<5; i++)
        a[i]=0;

    do
    {
//C is 1 by default

        if(c==1)
        {
            printf("\npress number in front of command that you would like to do\n");
            printf("1 - non-rechargeable batteries\n2 - cart summary\n");
            printf("Enter : ");
            scanf("%d",&choice);

            switch(choice)
            {
            case 1:
            {
                int nonRechargeableBatteries;
                printf("\nselect various kind of battery to buy\n1 - Aluminium–air battery\n2 - Bunsen cell\n3 - Dry cell\nAny other number to exit\n");
                scanf("%d",&nonRechargeableBatteries);

                switch(nonRechargeableBatteries)
                {
                case 1:
                {
                    int num;
                    printf("You chose Aluminium–air battery.\nPress 1 to add to the cart.\nAny other number to cancel\n");
                    scanf("%d",&num);
                    if(num==1)
                    {
                        printf("enter how many items you want : ");
                        scanf("%d",&quantity);
                        a[0]+=quantity;
                        totalCost = add(totalCost,input[0].cost,quantity);
                    }
                    break;
                }
                .
                .
                .
                }
                break;
            }

            case 2:
            {
                printf("No\tItems%-21sQuantity\tCost\n"," ");

                for(i = 0 ; i<5 ; i++,ptr++)
                {
                    if(a[i]!=0)
                    {
                        printf("%d\t%s%-4s%d\t\t%d\n",input[i].No,input[i].singleitem," ",a[i],(input[i].cost*a[i]));
                    }

                }
                printf("\nTotal Cost\t\t\t\t\t%d\n",totalCost);
                printf("continue shopping Enter\n1 to Add Item\n2 to Delete Items\n3 Add or subtract existing item(s) in cart \nAny other number to Exit\n");
                scanf("%d",&c);
            }

            default:
            {
                if(c==1)
                    printf("Enter Valid Categories Choice\n");
                else;
                break;
            }
            }
            if(choice>0&&choice<2)
            {
                printf("No\tItems%-21sQuantity\tCost\n"," ");
                for(i=0; i<5; i++)
                {
                    if(a[i]!=0)
                    {
                        printf("%d\t%s%-4s%d\t\t%d\n",input[i].No,input[i].singleitem," ",a[i],(input[i].cost*a[i]));
                    }
                }
                printf("\nTotal Cost\t\t\t\t\t%d\n",totalCost);
                printf("continue shopping Enter\n1 to Add Item\n2 to Delete Items\n3 Add or subtract existing item(s) in cart \nAny other number to Exit\n");
                scanf("%d",&c);
            }
            else;
            
        }
        }
    while(c==1 || c==2 ||c==3);
    printf("Your total cost is %d\n",totalCost);}