Dynamic queue Create a linked list of student records (at least 15) and put all

Question

Dynamic queue

Create a linked list of student records (at least 15) and put all the related student records information in it: Student ID(Axxxxxxxx), Name, Address and average of test scores and a Pointer for Test Scores (at least 10 scores).

-Display the student records in the linked list and the average of scores (do not display pointers).

-Enqueue all student records from the linked list to a dynamic queue.

-Dequeue 5 student records from the dynamic queue and display the extracted records.

-Display the remaining student records in the dynamic queue.

(Loops are needed, Dynamic queue Class definition must be used, using template and container is optional.(C++) )

Explanation / Answer

Dynamic Memory Allocation and Dynamic Structures

Dynamic allocation is a pretty unique feature to C (amongst high level languages). It enables us to create data types and structures of any size and length to suit our programs need within the program.

We will look at two common applications of this:

·                     dynamic arrays

Malloc, Sizeof, and Free

The Function malloc is most commonly used to attempt to ``grab'' a continuous portion of memory. It is defined by:

void *malloc(size_t number_of_bytes)

That is to say it returns a pointer of type void * that is the start in memory of the reserved portion of size number_of_bytes. If memory cannot be allocated a NULL pointer is returned.

Since a void * is returned the C standard states that this pointer can be converted to any type. The size_t argument type is defined in stdlib.h and is an unsigned type.

So:

    char *cp;

                               cp = malloc(100);

attempts to get 100 bytes and assigns the start address to cp.

Also it is usual to use the sizeof() function to specify the number of bytes:

    int *ip;

                               ip = (int *) malloc(100*sizeof(int));

Some C compilers may require to cast the type of conversion. The (int *) means coercion to an integer pointer. Coercion to the correct pointer type is very important to ensure pointer arithmetic is performed correctly. I personally use it as a means of ensuring that I am totally correct in my coding and use cast all the time.

It is good practice to use sizeof() even if you know the actual size you want -- it makes for device independent (portable) code.

sizeof can be used to find the size of any data type, variable or structure. Simply supply one of these as an argument to the function.

SO:

In the above we can use the link between pointers and arrays to treat the reserved memory like an array. i.e we can do things like:

   ip[0] = 100;

or

   for(i=0;i<100;++i) scanf("%d",ip++);

Full Program: queue.c

A queue is basically a special case of a linked list where one data element joins the list at the left end and leaves in a ordered fashion at the other end.

The full listing for queue.c is as follows:

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