/*      Introduction to program:
        Program - dynavg.c.
        Example of dynamic memory allocation.
        Based on P93.c from Paul Kelly's "A guide to C programming".
        Francis O'Donovan 21-1-98. */

/* Files to be included. */
 
#include <stdio.h>
#include <stdlib.h>

/*      Function: main(). */

main()
{
        /* Initialize variables. */

        int *int_array;         /* Pointer to array. */
        int no_els, no_bytes, i;/* The number of elements, bytes and a counter. */
        int average;            /* The average of the numbers. */

        /* Print introduction on screen. */

        printf( "Program: dynavg.c.\n" );
        printf( "Example of dynamic memory allocation.\n" );
        printf( "Based on P93.c from Paul Kelly\'s \"A guide to C programming\".\n" );
        printf( "Francis O'Donovan 21-1-98.\n\n" );

        /* Ask user how many numbers will be inputted. */

        printf( "Please type in the number of integers whose average is to be calculated.\n" );
        scanf( "%d", &no_els );

        /* Calculate the number of bytes required by array for the numbers inputted. */

        no_bytes = no_els * sizeof(int);

        /* Try to allocate memory, and return error if fail. */

        int_array = malloc (no_bytes);

        if ( int_array == NULL )
        {
                printf( "Cannot allocate memory for array!!!!\n" );
                printf( "Program terminated. Goodbye!\n" );
        }
        else
        {
                /* Enter elements into array. */
                /* As the numbers are entered, add them together. */

                average = 0;

                printf( "Please type integers only.\n" );

                for ( i = 0; i < no_els; i++ )
                {
                        printf( "\nEnter number %d: ", i+1 );
                        scanf( "%d", int_array+i );
                        average += *(int_array+i);
                }

                /* Calculate average of numbers by dividing average by no_els. */

                average /= no_els;

                /* Output average and free memory. */

                printf( "The average (int form) is %d.\n", average );
                free ( int_array );
        }
}

© Francis O'Donovan 1999.