Question :
(a) Describe what are streams in file handling and explain what should be done when accessing data in an existing file.
(b) For what purpose are StreamReader and StreamWriter classes used?
(c) Write a program to add the details of 10 products of a supermarket in the text file (product.doc). The details of the products are product ID, product name, quantity and unit price.
(d) Using the file in 3(c), write appropriate codes to perform the following tasks:
(i) Search for a product by its ID and display the details if it exists.
(ii) Compute the cost for each product and store the results in the fifth column of the file. Compute and display the total cost for the products in a textbox. Your answer should include validations.