Need to create a file and migrate user-selected items while deleting those same items in the original file?

Question

Arrays

Formation of a release note - which is a separate dynamic array, where the goods selected from the warehouse are entered, the quantity cannot exceed the flow in the warehouse, the issuance of goods for the invoice - reduces the corresponding quantities in the warehouse, saving the warehouse in a binary file and reading from it. Keep in mind that the entire warehouse fits in RAM and does not require reading in parts.