Lab -5 More on Pointers- Learn to use pointers and operators at a more advanced level using C programming

#include <stdio.h>
/*
Title: Lab #5a: More on Pointer-Pointer Operators
Objective: Document every line of code and explaining its function
and output.
*/

int main()
{
int a = 7 ; //value a is 7
int *aPtr ; //pointer variable
aPtr = &a ; // points to address of a

printf( "%p\n", &a ); //prints address of a
printf( "%p\n", aPtr ); //prints address of a
printf( "%p\n", &aPtr ); //prints address of pointer to a
printf( "%d\n", a ); //prints value of 'a'
printf( "%d\n", *aPtr ); //prints value 7
printf( "%p\n", *&aPtr ); //prints value of pointer (address of a)
printf( "%p\n", &*aPtr ); //prints address of a
printf( "%d\n", *&a ); //prints the value of 'a'
//printf( "%d", &*a ); //error can't deallocate value

return 0;
}

/*
Output
------

0060FF0C
0060FF0C
0060FF0B
7
7
0060FF0C
0060FF0C
7

*/

B. Array Manipulation with Pointers
Write, document and test each of the following function specifications (write your code for this part in a file called: Lab5b.c):
[You should use only pointer arithmetic – DO NOT USE array indices (i.e. subscripts)].
1. A function called FillArray() that accepts a pointer to a integer as the array name, an integer for its size. This function pseudo-randomly fills the array with integers ranging from 0 to 100. Do not be concerned about possible duplicate values.
2. A function called PrintArray() that accepts a pointer to a integer as the array name, an integer for its size. This function only prints the array elements.
3. A function called BubbleSort() that accepts a pointer to a integer as the array name, an integer for its size. The function should sort the array passed, in descending order. Use the function Swap() that you designed in the last Lab #4, to swap any values in the function BubbleSort().
4. In the main() function:
a. Declare an integer array called NumList of size SIZE (define SIZE as 20, using #define).
b. Populate the array with pseudo-random numbers [0 -100] by calling the function FillArray().
c. Display the Array contents by calling the function PrintArray().
d. Sort the array NumList in descending order by calling the function BubbleSort().
e. Display the SORTED array by calling the function PrintArray().
For your convenience, the function prototypes are given bellow:
void FillArray ( int *array, int size );
void PrintArray ( int *array, int size );
void BubbleSort ( int *array, int size );
void Swap ( int *x, int *y );

Answer:

/*
Title: Lab #5b: More on Pointer - Array Manipulation with Pointers
Objective: Document every line of code and explaining its function
and output.
*/

//Includes
#include <stdio.h>//C-Preprocessor Directives
#include <time.h>//C-Preprocessor Directives

//Declare CONSTANTS
#define SIZE 20

//Function Prototypes
void FillArray ( int *array, int size );
void PrintArray ( int *array, int size );
void BubbleSort ( int *array, int size );
void Swap ( int *x, int *y );

int main(){
	//Declare an integer array NumList
    int NumList[SIZE];
	//call the function to populate the array
	FillArray( NumList, SIZE );
	printf("\n Unsorted :\n");
	//call the function to display the array
	PrintArray( NumList, SIZE );
	//call the function to sort the array using bubbleSort
	BubbleSort( NumList, SIZE );
	printf("\n Sorted :\n");
	//call the function to display the array after sorting in descending order 
	PrintArray( NumList, SIZE );

	return 0;
}

/*
	Objective: Populate the array with pseudo-random numbers from 0-100
	input: an array and its size
	output: array with 20 random numbers
*/
void FillArray (int *array, int size){
	//seeding
	srand(time(NULL));
	//Variable Declaration
	int random,i;
	//Choose 20 random number ranged from 1 to 100
	for ( i = 0; i < size; i++){
		random = rand() % 101;
		*(array + i) = random;
	}
}

/*
	Objective: Display the elements of the array on the screen
	input: an array and the size of the array
	output: Display elements of the array
*/
void PrintArray (int *array, int size){
    int i;
	for ( i = 0; i < size; i++){
		printf("%d ", *(array + i));
	}
	//new line
	printf ("\n");
}

/*
	Objective: sort the array in descending order using bubble sort
	input: an array and the size of the array
	output: sorted array in decending order
*/
void BubbleSort (int *array, int size){
    int i,j;
	for ( i = 0; i < size ; i++){
		for ( j = 0 ; j < size - i; j++){
			if (*(array + j) < *(array + j + 1)){
				Swap (array + j, array + j + 1);
			}
		}
	}
}

/*
	Objective: Swap two adjacent numbers in an array 
	input: Two adjacent numbers in an array x.y
	output: two consecutive numbers sorted the higher first then the lowest
*/
void Swap (int *x, int *y){
	int temp = *x;
	*x = *y;
	*y = temp;
}