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#include <stdio.h>

typedef struct {
    int nnnn;
    char description[32];
    char type;
    int qty;
} Transaction;

typedef struct {
    int nnnn;
    char description[32];
    double price;
    int in_stock;
    int back_order;
} Product;


void manageInventory(Transaction t, int inventory[]) {
  	//  ‘D’		Delivery = +1
	  // ‘R’		Return = +1
	  // ‘P’ 		Purchase = +1
    
    if (t.type == 'P') {
        inventory[t.nnnn] -= t.qty;
    } else if (t.type == 'R' || t.type == 'D') {
        inventory[t.nnnn] += t.qty;
    }
}

int main() {
    FILE *fp;
    Transaction t;

    int inventory[9999] = {0};
    Product product;

    fp = fopen("transaction.dat", "r");

    if (fp == NULL) {
        printf("File could not be opened.");
        return 1;
    }

    while (fscanf(fp, "%d %31[^\t] %c %d\n", &t.nnnn, t.description, &t.type, &t.qty) == 4) {
        manageInventory(t, inventory);
    }

    fclose(fp);

    fp = fopen("datafile.dat", "r");

    FILE *fp2;
    fp2 = fopen("output.dat", "w");

    if (fp == NULL) {
        printf("File could not be opened.");
        return 1;
    }

    while (fscanf(fp, "%d %31[^\t] %lf %d %d\n", &product.nnnn, product.description, &product.price, &product.in_stock, &product.back_order) == 5) {
        int inv = inventory[product.nnnn];

        if (inv > 0){
          // first do the back order then the in stock
          if (inv >= product.back_order) {
            product.in_stock += (inv - product.back_order);
            product.back_order = 0;
          } else {
            product.back_order -= inv;
          }
        } else if(inv < 0) {
          product.back_order += (-1 * inv);
        }
      fprintf(fp2, "%d\t%s\t%.2lf\t%d\t%d\n", product.nnnn, product.description, product.price, product.in_stock, product.back_order);
    } 

    fclose(fp);
    fclose(fp2);
    return 0;
}