December 1999
CA208 : 'C' PROGRAMMING

QUESTION 2

Total Marks: 15 Marks

• Question 1
• Question 3
• Question 4
• Question 5
• Cover Page

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for Question 2

You are to implement a task queueing system.When a task is entered into the system,it has assigned to it a priority,which is one of low,medium or high,and a name,which is a string of arbitrary length.The definition of the queue is given below,where front points to the first task in Q ,back points to the last task in Q .A task contains a link to the next task in Q .

Define a suitable enumerated type,priority ,which can take on any one of the values low ,medium or high .

Define a suitable data structure task ,which can be used to hold the following information about a task:

•The task priority of the task;
•The name of the task;
•A pointer next ,which will point to the next task in the queue.

Write a function,called IsEmpty ,the signature of which is given below,which takes in a pointer to a queue x ,and returns 1 if the queue is empty,and 0 otherwise.You may assume that an empty queue will have NULL pointers for the head and the tail.

int IsEmpty(task queue*x);

Write a function,called Head ,the signature of which is given below,which takes in a queue x of type task queue ,and removes the item at the head of the queue,should the queue be non empty.The item should be returned as the reference parameter y , and the function should return the number of items which have been successfully removed from the queue.

int Head(task queue*x,task*y);