COMPUTER SCIENCE- PAPER 2

Variables and constants are used for data storage in computer programs. Discuss the similarities and differences between these data stores.

A programmer is writing a program that stores data about items stored in a warehouse. Suggest suitable meaningful names and data types for: Item name, Number in stock, Reorder level, Whether the item is on order or not.

Answer explanation

Item name should be of type string, Number in stock and Reorder level should be of type integer, and Whether the item is on order or not should be of type boolean.

Programming concepts include: selection, totalling, counting. Describe each and provide an example of program code to show how it is used.

Answer explanation

Selection involves choosing between different paths based on conditions. Totalling is the summing of values. Counting is keeping track of occurrences. Example: Selection - if-else statement. Totalling - summing an array. Counting - counting occurrences in a list.

Programs can use both local and global variables. Describe, using examples, the difference between local and global variables.

Answer explanation

Local variables are declared within a specific function or block and can only be accessed within that scope. Global variables are declared outside of any function and can be accessed from anywhere in the program.

A two-dimensional array stores the first name and family name of fifteen people. Write a program in pseudocode to display the first name and family name of the fifteen people.

Answer explanation

Create a loop to iterate through the two-dimensional array and display the first name and family name of each person.

Extend your program to sort the ten names in order of family name before displaying the names.

Answer explanation

To sort the names by family name, you can split each name into first and last names, then sort based on the last name. This can be achieved by using string manipulation functions or regular expressions to extract the last name for sorting.

Describe the purpose of each statement in this algorithm. FOR I ← 1 TO 300, INPUT Name[I], NEXT I.

Answer explanation

The FOR loop iterates from 1 to 300, INPUT Name[I] stores input in array at index I, and NEXT I increments the loop counter.

State one validation check that has been used in this algorithm.

Answer explanation

One validation check used in this algorithm is ensuring that the input data falls within the specified range or limits.

This algorithm makes sure that there are enough wheelbarrows in stock. Complete the trace table for the algorithm using this input data: “Y”, “Y”, “Y”, “Y”, “Y”, “Y”, “N

Answer explanation

The trace table will have columns for each input letter, marking 'Y' for each 'Y' input and 'N' for the last 'N' input to track stock availability.

A database table, PERFORMANCE, is used to keep a record of the performances at a local theatre. State the number of fields and records in the table.

Answer explanation

The number of fields in the table refers to the columns in the table, and the number of records refers to the rows in the table.