I know the concepts behind "fstream", like ifstream and ofstream, but what exactly is istream? For example, say there is a function with this heading:
What does that &input variable hold exactly? Can someone assist me with some examples? Thanks.Code:void ChangePrices(GroceryStore &store, istream &input); // Precondition: Input is open for reading. // Each line consists of a valid one word item name // and a valid price. // Postcondition: Changes the prices of items in store using names // and new prices from input.