C – Practical System Programming for Graphics in C.

Practical System Programming for Graphics in C

By Shritam Bhowmick
Web Application Penetration Tester
LinkedIn: https://www.linkedin.com/profile/view?id=281014248&trk=nav_responsive_tab_profile
Academia: https://independent.academia.edu/ShritamBhowmick
Facebook: https://www.facebook.com/coded32

This is an introduction post for “Graphics and Internet” for WBUT 2014, which includes C as system programming and the underlying source code concepts for drawing basic graphics using C. Earlier in this post, I discussed data-structures in C for WBUT University in details which covered the practical aspects of year 2014. This post in contrary will mention the graphical aspect of the C programming keeping in mind the practical labs. I am glad I could post as far as the syllabus is concerned (which is really outdated as discussed in the last post), but this will help the current students who could have a look here after 2014 passes.

===========================================================================

1.) Draw a Basic Circle:

#include
#include

main()
{
int gd = DETECT, gm;

initgraph(&gd, &gm, "C:TCBGI");

circle(100, 100, 50);

getch();
closegraph();
return 0;
}

===========================================================================

2.) Draw a Rainbow

#include
#include
#include
#include

void main()
{
int gdriver = DETECT,gmode;
int x,y,i;
initgraph(&gdriver,&gmode,"C:TurboC4BGI");
x=getmaxx()/2;
y=getmaxy()/2;
for(i=30;i<200;i++)
{
delay(100);
setcolor(i/10);
arc(x,y,0,180,i-10);
}
getch();
}

===========================================================================

3.) Draw a Smiley

#include
#include
#include
#include

void main()

{
int gd=DETECT,gm;
initgraph(&gd,&gm,"C:BGI");
outtextxy(150,10,"This is a program to draw a Smiley Asshole!");
circle(200,200,80);
circle(160,180,8);
circle(240,180,8);
arc(200,230,180,360,20);
line(190,245,210,260);
line(210,245,210,260)
arc(200,260,180,360,9);
line(200,180,195,210);
arc(202,210,190,10,8);
getch();
closegraph();

}

===========================================================================

4.) Draw a Diagonal Line

#include < stdio.h >
#include < conio.h >
#include < graphics.h >

void main()
{
int gdriver=DETECT,gmode=0;
initgraph(&gdriver, &gmode, "c:tcbgi");
line(0,0,getmaxx(),getmaxy());
getch();
closegraph();

}

===========================================================================

5.) Draw an Eclipse

#include
#include

main()
{
int gd = DETECT, gm;

initgraph(&gd, &gm, "C:TCBGI");

ellipse(100, 100, 0, 360, 50, 25);

getch();
closegraph();
return 0;
}

===========================================================================

5.) Draw a Triangle

#include
#include
#include

void main() {
int gd = DETECT, gm;
initgraph(&gd, &gm, "c:tcbgi");

line(300, 100, 200, 200);
line(300, 100, 400, 200);
line(200, 200, 400, 200);

getch();
closegraph();
}

There are others as well which are related to Web Development. The posts belonging to Web-development could already be accessed from here. The section is for everything related to ‘code’ and working with code in different languages. HTML could be found there. I would appreciate if the readers leave behind a feedback. Roger out./-

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Data Structures in C Practicals and Why Colleges with their IDE’s are Outdated. A Wiser Proof of Concept.

Data Structures in C and Why Colleges with their IDE’s are Outdated!

By Shritam Bhowmick
Web Application Penetration Tester
LinkedIn: https://www.linkedin.com/profile/view?id=281014248&trk=nav_responsive_tab_profile
Academia: https://independent.academia.edu/ShritamBhowmick
Facebook: https://www.facebook.com/coded32

The Introduction Preface

Hi, this is about all the practical lab C  for WBUT Winters (Semester 3rd of the University prescribed Syllabus) section data-structures questions solved at once place for a ready reference to the students who might seek help and also on an information as to why colleges now should be moving from the stone age. All the programs are complied under Tubro C++ compiler and would not be/should not be expected to be executed/processed to create an object under GNU C compiler or  any Windows variant compilers (such as Visual C compiler). Since the syllabus itself is too outdated and people had been talking about them in various forums; I came up with a compilation of the code as well as the questions which could help them understand the core with the ready service code to be executed only within from Turbo C++ compiler. This is C code and not C++ code. The source code for each of them had been practically tested on Windows 8.1 platform using DOSBOX as an emulator to run Turbo C.

The Recommendations

It’s recommended to move on with the syllabus and pay less attention there, if anyone really is serious on C and C++ programming. Python, Ruby, Delphi, Lua and Perl are the modern spectacular languages to choose from and Java is really not that friendly as you might think if you have to do a certain task. Java isn’t that flexible in terms that Java would really need long source code for a simple problem. See “Python to other languages – A comparison“. Get to know more at Stackoverflow. To refernce from the original source, here’s is the justification why someone would prefer to code in Python rather than any other older languages in a nutshell:

  1. Speed of development. I can crank out working code before the Java folks have stuff that will compile.
  2. Flexibility. I can refactor and rework a module in an afternoon. The Java folks have to redesign things on paper to be sure they can get some of the bigger refactorings to recompile. In Java, the changes aren’t as small and focused.I should probably blog about some of the nastier refactorings that would be a huge pain — even using the refactoring tools in Eclipse or NetBeans. The most recent example was a major change to the top-most superclass of a class hierarchy that would have invalidated a mountain of Java code. But the method was used in exactly two places, allowing a trivial change to the superclass and those two places. 100’s of unit tests passed, so I’m confident in the change without the compiler overhead.
  3. Simplicity. Python doesn’t need a sophisticated IDE and super-complex WS libraries. Python code can be written in Komodo Edit. A WS interface between your Java front-end and PostgresSQL can be knocked together in Werkzeug in a day. You can plug your transactions into this without much overhead.

The post primarily covered Python against Java, but there are instances why some one could just prefer Python over C which could be referenced from here in this post. This does not at all mean to compare C and Python on basis of what they have to deliver but rather compares them on an average on the end-users opinion perspective. There are other considerations as well into modern computing which is resolved below in the list.

Why Would Python be Slow but equivalently faster ever than C Deployments?

Python is a higher level language than C, which means it abstracts the details of the computer from you – memory management, pointers, etc, and allows you to write programs in a way which is closer to how humans think. It is true that C code usually runs 10 to 100 times faster than Python code if you measure only the execution time. However if you also include the development time Python often beats C. For many projects the development time is far more critical than the run time performance. Longer development time converts directly into extra costs, fewer features and slower time to market.

Why use C contrary to the switching to any other programming languages, a hope out of no-where!?

“If there ever were a quote that described programming with C, it would be this. To many programmers, this makes C scary and evil. It is the Devil, Satan, the trickster Loki come to destroy your productivity with his seductive talk of pointers and direct access to the machine. Then, once this computational Lucifer has you hooked, he destroys your world with the evil “segfault” and laughs as he reveals the trickery in your bargain with him.

But, C is not to blame for this state of affairs. No my friends, your computer and the Operating System controlling it are the real tricksters. They conspire to hide their true inner workings from you so that you can never really know what is going on. The C programming language’s only failing is giving you access to what is really there, and telling you the cold hard raw truth. C gives you the red pill. C pulls the curtain back to show you the wizard. C is truth. Why use C then if it’s so dangerous? Because C gives you power over the false reality of abstraction and liberates you from stupidity.”

The Coverage

Now since we are already hopped into C with Turbo C as a compiler. I’d go writing the source code of the practicals here and try to keep it updated as much as I could to my disposal. Instead this is the responsibility at your side to post back with comments on what else its to be added so this could help others in the process.

Notes

The source code has replaced all the instances of \n to n. Take care of that plus the include headers have not been defined to be kept away from copy/paste practices. This in my opinion will lead to a better coding practices and would lead to a great start with self-research.

The Question Set

The questions I have dug so far follows these:

  1. Doubly Linked List with insertion and deletion.
  2. Priority Queue with addition and deletion of elements.
  3. Dequeue or Double Ended Queue using Linked List.
  4. Dequeue or Double Ended Queue using Circular Array.
  5. Priority Queue Implementation using Arrays.
  6. Circular Queue using Linked List with Circular Queue Concept Notes.
  7. Circular Queue Implementation in C Data-Structures using Arrays.
  8. Stack for PUSH and POP operations in C both via recursive and regular methods.
  9. Linear Search Implementation in C using Arrays.
  10. Binary Search Implementation in C using Arrays.
  11. Insertion Sort Implementation in C using Arrays.
  12. Merge Sort Implementation in C using Arrays.
  13. Quick Sort Implementation in C using Arrays.
  14. Heap Sort Implementation in C using Arrays.

Source Code Solutions

1.) Doubly Linked List with Insertion, Deletion and Reverse Display

Here’s the source code (to avoid copy/paste gimmicks, I have stripped off all the includes. Feel free to add them at your own expense) for Doubly Linked List:

#include
#include
#include
struct node
{
struct node *previous;
int data;
struct node *next;
}*head, *last;

void insert_beginning(int value)
{
struct node *var,*temp;
var=(struct node *)malloc(sizeof(struct node));
var->data=value;
if(head==NULL)
{
head=var;
head->previous=NULL;
head->next=NULL;
last=head;
}
else
{
temp=var;
temp->previous=NULL;
temp->next=head;
head->previous=temp;
head=temp;
}
}

void insert_end(int value)
{
struct node *var,*temp;
var=(struct node *)malloc(sizeof(struct node));
var->data=value;
if(head==NULL)
{
head=var;
head->previous=NULL;
head->next=NULL;
last=head;
}
else
{
last=head;
while(last!=NULL)
{
temp=last;
last=last->next;
}
last=var;
temp->next=last;
last->previous=temp;
last->next=NULL;
}
}

int insert_after(int value, int loc)
{
struct node *temp,*var,*temp1;
var=(struct node *)malloc(sizeof(struct node));
var->data=value;
if(head==NULL)
{
head=var;
head->previous=NULL;
head->next=NULL;
}
else
{
temp=head;
while(temp!=NULL && temp->data!=loc)
{
temp=temp->next;
}
if(temp==NULL)
{
printf("n%d is not present in list ",loc);
}
else
{
temp1=temp->next;
temp->next=var;
var->previous=temp;
var->next=temp1;
temp1->previous=var;
}
}
last=head;
while(last->next!=NULL)
{
last=last->next;
}
}
int delete_from_end()
{
struct node *temp;
temp=last;
if(temp->previous==NULL)
{
free(temp);
head=NULL;
last=NULL;
return 0;
}
printf("nData deleted from list is %d n",last->data);
last=temp->previous;
last->next=NULL;
free(temp);
return 0;
}

int delete_from_middle(int value)
{
struct node *temp,*var,*t, *temp1;
temp=head;
while(temp!=NULL)
{
if(temp->data == value)
{
if(temp->previous==NULL)
{
free(temp);
head=NULL;
last=NULL;
return 0;
}
else
{
var->next=temp1;
temp1->previous=var;
free(temp);
return 0;
}
}
else
{
var=temp;
temp=temp->next;
temp1=temp->next;
}
}
printf("data deleted from list is %d",value);
}

void display()
{
struct node *temp;
temp=head;
if(temp==NULL)
{
printf("List is Empty");
}
while(temp!=NULL)
{
printf("-> %d ",temp->data);
temp=temp->next;
}
}

int main()
{
int value, i, loc;
head=NULL;
printf("Select the choice of operation on link list");
printf("n1.) insert at begningn2.) insert at atn3.) insert at middle");
printf("n4.) delete from endn5.) reverse the link listn6.) display listn7.)exit");
while(1)
{
printf("nnenter the choice of operation you want to do ");
scanf("%d",&i);
switch(i)
{
case 1:
{
printf("enter the value you want to insert in node ");
scanf("%d",&value);
insert_beginning(value);
display();
break;
}
case 2:
{
printf("enter the value you want to insert in node at last ");
scanf("%d",&value);
insert_end(value);
display();
break;
}
case 3:
{
printf("after which data you want to insert data ");
scanf("%d",&loc);
printf("enter the data you want to insert in list ");
scanf("%d",&value);
insert_after(value,loc);
display();
break;
}
case 4:
{
delete_from_end();
display();
break;
}
case 5:
{
printf("enter the value you want to delete");
scanf("%d",value);
delete_from_middle(value);
display();
break;
}
case 6 :
{
display();
break;
}
case 7 :
{
exit(0);
break;
}
}
}
printf("nn%d",last->data);
display();
getch();
}

2.) Priority Queue with Addition and Deletion of Elements

#include
#include
#define MAX 5

void insert_by_priority(int);
void delete_by_priority(int);
void create();
void check(int);
void display_pqueue();

int pri_que[MAX];
int front, rear;

void main()

{

int n, ch;
printf("n1 - Insert an element into queue");
printf("n2 - Delete an element from queue");
printf("n3 - Display queue elements");
printf("n4 - Exit");
create();

while (1)

{

printf("nEnter your choice : ");

scanf("%d", &ch);

switch (ch)

{

case 1:

printf("nEnter value to be inserted : ");

scanf("%d",&n);

insert_by_priority(n);

break;

case 2:

printf("nEnter value to delete : ");

scanf("%d",&n);

delete_by_priority(n);

break;

case 3:

display_pqueue();

break;

case 4:

exit(0);

default:

printf("nChoice is incorrect, Enter a correct choice");

}

}

}

/* Function to create an empty priority queue */

void create()

{

front = rear = -1;

}

/* Function to insert value into priority queue */

void insert_by_priority(int data)

{

if (rear >= MAX - 1)

{

printf("nQueue overflow no more elements can be inserted");

return;

}

if ((front == -1) && (rear == -1))

{

front++;

rear++;

pri_que[rear] = data;

return;

}

else

check(data);

rear++;

}

/* Function to check priority and place element */

void check(int data)

{

int i,j;

for (i = 0; i <= rear; i++) { if (data >= pri_que[i])

{

for (j = rear + 1; j > i; j--)

{

pri_que[j] = pri_que[j - 1];

}

pri_que[i] = data;

return;

}

}

pri_que[i] = data;

}

/* Function to delete an element from queue */

void delete_by_priority(int data)

{

int i;

if ((front==-1) && (rear==-1))

{

printf("nQueue is empty no elements to delete");

return;

}

for (i = 0; i <= rear; i++)

{

if (data == pri_que[i])

{

for (; i < rear; i++)

{

pri_que[i] = pri_que[i + 1];

}

pri_que[i] = -99;

rear--;

if (rear == -1)

front = -1;

return;

}

}

printf("n%d not found in queue to delete", data);

}

/* Function to display queue elements */

void display_pqueue()

{

if ((front == -1) && (rear == -1))

{

printf("nQueue is empty");

return;

}

for (; front <= rear; front++)

{

printf(" %d ", pri_que[front]);

}

front = 0;

}

3.) Dequeue or Double Ended Queue using Linked List

What is Dequeue?

The word dequeue is short form of double ended queue. In a dequeue , insertion as well as deletion can be carried out either at the rear end or the front end. The following diagram illustrates a version of the same concept:

Dequeue Represented Using a Circular Array

The source code is available below:

#define MAX 100
#include
#include

void insert(int);
int delStart();
int delEnd();
int queue[MAX];
int rear =0, front =0;
void display();
void insertEnd(int);
void insertStart(int);

int main()
{
char ch , a='y';
int choice, c, token;
printf("Enter your choice for which deque operation you want to perform operation n");
do
{
printf("n1.Input-restricted deque n");
printf("2.output-restricted deque n");
printf("nEnter your choice for the operation : ");
scanf("%d",&c);
switch(c)
{
case 1:
printf("nDo operation in Input-Restricted c dequen");
printf("1.Insert");
printf("n2.Delete from end");
printf("n3.Delete from begning");
printf("n4.show or display");
do
{
printf("nEnter your choice for the operation in c deque: ");
scanf("%d",&choice);
switch(choice)
{
case 1: insertEnd(token);
display();
break;
case 2: token=delEnd();
printf("nThe token deleted is %d",token);
display();
break;
case 3: token=delStart();
printf("nThe token deleted is %d",token);
display();
break;
case 4: display();
break;
default:printf("Wrong choice");
break;
}
printf("nDo you want to continue(y/n) to do operation in input-restricted c deque: ");
ch=getch();
}
while(ch=='y'||ch=='Y');
getch();
break;

case 2 :
printf("nDo operation in Output-Restricted c dequen");
printf("1.Insert at the End");
printf("n2.Insert at the begning");
printf("n3.Delete the element");
printf("n4.show or display");
do
{
printf("nEnter your choice for the operation: ");
scanf("%d",&choice);
switch(choice)
{
case 1: insertEnd(token);
display();
break;
case 2: insertStart(token);
display();
break;
case 3: token=delStart();
printf("nThe token deleted is %d",token);
display();
break;
case 4: display();
break;
default:printf("Wrong choice");
break;
}
printf("nDo you want to continue(y/n):");
ch=getch();
}
while(ch=='y'||ch=='Y');
getch();
break ;
}

printf("nDo you want to continue(y/n):");
ch=getch();
}
while(ch=='y'||ch=='Y');
getch();
}

void display()
{
int i;
printf("nThe queue elements are:");
for(i=rear;i<front;i++)
{
printf("%d  ",queue[i]);
}
}

void insertEnd(int token)
{
char a;
if(front==MAX/2)
{
printf("nQueue fullnyou cant enter more elements at the end of c queue");
return;
}
do
{
printf("nEnter the token to be inserted:");
scanf("%d",&token);
queue[front]=token;
front=front+1;
printf("do you want to continue insertion Y/N");
a=getch();
}
while(a=='y');
}

void insertStart(int token)
{
char a;
if(front==MAX/2)
{
printf("nQueue fullnyou cant enter more elements at the start of queue");
return;
}
do
{
printf("nEnter the token to be inserted:");
scanf("%d",&token);
rear=rear-1;
queue[rear]=token;
printf("do you want to continue insertion Y/N");
a=getch();
}
while(a=='y');
}
int delEnd()
{
int t;
if(front==rear)
{
printf("nQueue empty");
return 0;
}
front=front-1;
t=queue[front+1];
return t;
}
int delStart()
{
int t;
if(front==rear)
{
printf("nQueue empty");
return 0;
}
rear=rear+1;
t=queue[rear-1];
return t;
}

4.) Dequeue or Double Ended Queue using Circular Array

The available source code is different from the previous one which used linked list. This time the code uses the concept for circular array and implements a Dequeue or Double Ended Queue implementation around circular array. The source code is below as per the references.

#include
#include

#define MAX 30

typedef struct dequeue
{
int data[MAX];
int rear,front;
}dequeue;

void initialize(dequeue *p);
int empty(dequeue *p);
int full(dequeue *p);
void enqueueR(dequeue *p,int x);
void enqueueF(dequeue *p,int x);
int dequeueF(dequeue *p);
int dequeueR(dequeue *p);
void print(dequeue *p);

void main()
{
int i,x,op,n;
dequeue q;
initialize(&q);

do
{
printf("n1.Createn2.Insert(rear)n3.Insert(front)n4.Delete(rear)n5.Delete(front)");
printf("n6.Printn7.ExitnnEnter your choice:");
scanf("%d",&op);

switch(op)
{
case 1: printf("nEnter number of elements:");
scanf("%d",&n);
initialize(&q);
printf("nEnter the data:");

for(i=0;i<n;i++) { scanf("%d",&x); if(full(&q)) { printf("nQueue is full!!"); exit(0); } enqueueR(&q,x); } break; case 2: printf("nEnter element to be inserted:"); scanf("%d",&x); if(full(&q)) { printf("nQueue is full!!"); exit(0); } enqueueR(&q,x); break; case 3: printf("nEnter the element to be inserted:"); scanf("%d",&x); if(full(&q)) { printf("nQueue is full!!"); exit(0); } enqueueF(&q,x); break; case 4: if(empty(&q)) { printf("nQueue is empty!!"); exit(0); } x=dequeueR(&q); printf("nElement deleted is %dn",x); break; case 5: if(empty(&q)) { printf("nQueue is empty!!"); exit(0); } x=dequeueF(&q); printf("nElement deleted is %dn",x); break; case 6: print(&q); break; default: break; } }while(op!=7); } void initialize(dequeue *P) { P->rear=-1;
P->front=-1;
}

int empty(dequeue *P)
{
if(P->rear==-1)
return(1);
return(0);
}

int full(dequeue *P)
{
if((P->rear+1)%MAX==P->front)
return(1);
return(0);
}

void enqueueR(dequeue *P,int x)
{
if(empty(P))
{
P->rear=0;
P->front=0;
P->data[0]=x;
}
else
{
P->rear=(P->rear+1)%MAX;
P->data[P->rear]=x;
}
}

void enqueueF(dequeue *P,int x)
{
if(empty(P))
{
P->rear=0;
P->front=0;
P->data[0]=x;
}
else
{
P->front=(P->front-1+MAX)%MAX;
P->data[P->front]=x;
}
}

int dequeueF(dequeue *P)
{
int x;
x=P->data[P->front];
if(P->rear==P->front)   //delete the last element
initialize(P);
else
P->front=(P->front+1)%MAX;
return(x);
}

int dequeueR(dequeue *P)
{
int x;
x=P->data[P->rear];
if(P->rear==P->front)
initialize(P);
else
P->rear=(P->rear-1+MAX)%MAX;
return(x);
}

void print(dequeue *P)
{
if(empty(P))
{
printf("nQueue is empty!!");
exit(0);
}

int i;
i=P->front;
while(i!=P->rear)
{
printf("n%d",P->data[i]);
i=(i+1)%MAX;
}
printf("n%dn",P->data[P->rear]);
}

5.) Priority Queue using Array

I noticed I didn’t updated a priority queue implementation using arrays. This is the reason the source code is here for a ready reference to the readers of the blog. Here is the original version of the source code which is tested against the terms and conditions posted before which should be able to run via a Turbo C compiler. Any other compiler just won’t work because the syllabus itself is outdated, and people (and universities) must realize this fast.

#include
#include
#define size 5

int queue[5][2] = {0};
int top = -1;
int bottom;

void push(int value, int pr)

{

int i,j,k;

if(top < size-1) { if(queue[top][1] > pr)

{

for(i=0;i<top;i++) { if(queue[i][1] > pr)

{

break;

}

}

for(j=top;j>=i;j--)

{

queue[j+1][0] = queue[j][0];

queue[j+1][1] = queue[j][1];

}

top++;

queue[i][0] = value;

queue[i][1] = pr;

}

else

{

top++;

queue[top][0] = value;

queue[top][1] = pr;

}

}

else

{

printf("queue overflow n");

}

}

void pop()

{

int i;

if(queue[0][0] == 0)

{

printf("n The queue is empty  n");

}

else

{

printf("After , dequeue the following value is erased n  %d n", queue[0][0]);

for(i=0;i<top;i++) { queue[i][0] = queue[i+1][0]; queue[i][1] = queue[i+1][1]; } queue[top][0] = 0; queue[top][1] = 0; top--; } } void display() { int i,j; printf("ElementtPriority n"); for(i=size - 1;i>=0;i--)

{

for(j=0;j<2;j++)

{

printf(" %dt",queue[i][j]);

}

printf("n");

}

}

int main()

{

int i,j, ch=0 ,value = 0,pr=0;

while(1)

{

printf("n Please Enter the choice. n");

printf("1 for Enqueue n 2 for Dequeue n 3 for displayn  5 for exit: t n");

scanf("%d",&ch);

switch(ch)

{

case 1:

printf("n Please Enter the number to be inserted: t ");

scanf("%d", &value);

printf("n Please Enter the priority: t ");

scanf("%d", &pr);

push(value,pr);

break;

case 2:

pop();

break;

case 3:

display();

break;

case 5:

exit(0);

default:

printf("You entered wrong choice!");

}
}
}

6.) Circular Queue using Linked List in C Data-structures with Notes

In a standard queue data structure re-buffering problem occurs for each dequeue operation. To solve this problem by joining the front and rear ends of a queue to make the queue as a circular queue
Circular queue is a linear data structure. It follows FIFO principle.

  • In circular queue the last node is connected back to the first node to make a circle.
  • Circular linked list fallow the First In First Out principle
  • Elements are added at the rear end and the elements are deleted at front end of the queue
  • Both the front and the rear pointers points to the beginning of the array.
  • It is also called as “Ring buffer”.
  • Items can inserted and deleted from a queue in O(1) time.

Circular Queue can be created in three ways. They are:

  • · Using single linked list
  • · Using double linked list
  • · Using arrays

Follow is the source code for implementing a Circular Queue in C using Linked List:

#include
#include
#define max 5
int q[max];
int rear = -1, front = -1;
void insert();
void delet();
void display();

void main()
{
char ch;
int choice;
do
{
clrscr();
printf("n1 -> Insert");
printf("n2 -> Delete");
printf("n3 -> Display");
printf("n0 -> Exit");

printf("nnEnter Your Choice -> ");
scanf("%d", &choice);
switch (choice)
{
case 1:
insert();
break;
case 2:
delet();
break;
case 3:
display();
break;
case 0:
exit();
default:
printf("nnInvalid Choice");
}
printf("nnDo u Want to Continue -> ");
ch = getche();
} while (ch == 'y' || ch == 'Y');
}

void insert()
{
int data;
if ((rear == max - 1 && front == 0) || rear == front - 1)
{
printf("nSorry! Q is Full");
}
else
{
printf("nEnter data You want to insert ->");
scanf("%d", &data);
if (front == -1)
{
front++;
rear++;
}
else if (rear == max - 1)
{
rear = 0;
}
else
{
rear++;
}
q[rear] = data;
printf("nnData inserted successfully");
}
}
void delet()
{
if (front == -1)
{
printf("nnSorry! Q is Empty");
}
else
{
if (front == rear)
{
front = rear = -1;
}
else if (front == max - 1)
{
front = 0;
}
else
{
front++;
}
printf("nElement deleted Successfully");
}
}

void display()
{
int i;
if (front == -1)
{
printf("nnSorry! Q is Empty");
}
else
{
printf("nn:: Queue Elements are ::n");
if (front <= rear)
{
for (i = front; i <= rear; i++)
{
printf("n%d", q[i]);
}
}
else
{
for (i = front; i < max; i++)
{
printf("n%d", q[i]);
}
for (i = 0; i <= rear; i++)
{
printf("n%d", q[i]);
}
}
}
}

7.) Circular Queue Implementation in C using Arrays

Earlier in the post, we talked about implementation circular queue using Linked List. This section talks about the same implementation but using arrays. The source code below could be used for the purposes to demonstrate the concepts:

#include
#include
#include
#define MAXSIZE 5
int cq[MAXSIZE];
int front,rear;
void main()
{
void add(int,int);
void del(int);
int will=1,i,num;
front = -1;
rear = -1;
clrscr();
printf("nProgram for Circular Queue demonstration through array");
while(1)
{
printf("nnMAIN MENUn1.INSERTIONn2.DELETIONn3.EXIT");
printf("nnENTER YOUR CHOICE : ");
scanf("%d",&will);
switch(will)
{
case 1:
printf("nnENTER THE QUEUE ELEMENT : ");
scanf("%d",&num);
add(num,MAXSIZE);
break;
case 2:
del(MAXSIZE);
break;
case 3:
exit(0);
default: printf("nnInvalid Choice . ");
}

} //end of  outer while
}               //end of main
void add(int item,int MAX)
{
//rear++;
//rear= (rear%MAX);
if(front ==(rear+1)%MAX)
{
printf("nnCIRCULAR QUEUE IS OVERFLOW");
}
else
{
if(front==-1)
front=rear=0;
else
rear=(rear+1)%MAX;
cq[rear]=item;
printf("nnRear = %d    Front = %d ",rear,front);
}
}
void del(int MAX)
{
int a;
if(front == -1)
{
printf("nnCIRCULAR QUEUE IS UNDERFLOW");
}
else
{
a=cq[front];
if(front==rear)
front=rear=-1;
else
front = (front+1)%MAX;
printf("nnDELETED ELEMENT FROM QUEUE IS : %d ",a);
printf("nnRear = %d    Front = %d ",rear,front);

}
}

Here is a similar implementation of a queue using array. The source code could be referenced from the below:

#include
#include
#define N 6

int queue[N]={0};
int rear=0,front=0;

void insert(void);
void del(void);
void disp(void);
void cre(void);

void main()
{
int user=0;

clrscr();
while(user!=4)
{
clrscr();
printf("nnnttt THE SIZE OF QUEUE IS %d",N);
printf("nt 1.INSERT");
printf("nt 2.DELETE");
printf("nt 3.DISPLAY");
printf("nt 4.EXIT");
printf("nt 5.CREATE");
scanf("%d",&user);
switch(user)
{
case 1:
insert();
break;
case 2:
del();
break;
case 3:
disp();
break;
case 4:
printf("nt THANK U");
break;
case 5:
cre();
break;
}
getch();

}
getch();
}

void insert(void)
{
int t;
if(rear<N)
{
printf("nt ENTER A VALUE IN QUEUE");
scanf("%d",&t);
queue[rear]=t;
rear++;
}
else
{
printf("nt Q OVERFLOW!!!!!!!!!!!!!!!");
}
}
void del(void)
{
int i;
printf("nt %d gets deleted.........",queue[front]);
queue[front]=0;
front++;
}
void disp(void)
{
int i;
for(i=front;i<rear;i++)
{
printf("nt %d",queue[i]);
}
}
void cre(void)
{

int t;
printf("nt ENTER A VALUE IN QUEUE");
scanf("%d",&t);
front=0;
queue[front]=t;
rear=front+1;
}

8.) Stack Implementation to perform PUSH and POP Operations

After having gone through the Queue utilities in C and discussing queue with circular based and using Linked List, here is the source code to implement Stack for PUSH and POP operations in C.

#include
#define MAXSIZE 5

struct stack
{
int stk[MAXSIZE];
int top;
};
typedef struct stack STACK;
STACK s;

void push(void);
int  pop(void);
void display(void);

void main ()
{
int choice;
int option = 1;
s.top = -1;

printf ("STACK OPERATIONn");
while (option)
{
printf ("------------------------------------------n");
printf ("      1    -->    PUSH               n");
printf ("      2    -->    POP               n");
printf ("      3    -->    DISPLAY               n");
printf ("      4    -->    EXIT           n");
printf ("------------------------------------------n");

printf ("Enter your choicen");
scanf    ("%d", &choice);
switch (choice)
{
case 1:
push();
break;
case 2:
pop();
break;
case 3:
display();
break;
case 4:
return;
}
fflush (stdin);
printf ("Do you want to continue(Type 0 or 1)?n");
scanf    ("%d", &option);
}
}
/*  Function to add an element to the stack */
void push ()
{
int num;
if (s.top == (MAXSIZE - 1))
{
printf ("Stack is Fulln");
return;
}
else
{
printf ("Enter the element to be pushedn");
scanf ("%d", &num);
s.top = s.top + 1;
s.stk[s.top] = num;
}
return;
}
/*  Function to delete an element from the stack */
int pop ()
{
int num;
if (s.top == - 1)
{
printf ("Stack is Emptyn");
return (s.top);
}
else
{
num = s.stk[s.top];
printf ("poped element is = %dn", s.stk[s.top]);
s.top = s.top - 1;
}
return(num);
}
/*  Function to display the status of the stack */
void display ()
{
int i;
if (s.top == -1)
{
printf ("Stack is emptyn");
return;
}
else
{
printf ("n The status of the stack is n");
for (i = s.top; i >= 0; i--)
{
printf ("%dn", s.stk[i]);
}
}
printf ("n");
}

Here is yet another version of Stack implementation but using recursive method:

#include

#include

struct node

{

int a;

struct node *next;

};

void generate(struct node **);

void display(struct node *);

void stack_reverse(struct node **, struct node **);

void delete(struct node **);

int main()

{

struct node *head = NULL;

generate(&head);

printf("nThe sequence of contents in stackn");

display(head);

printf("nInversing the contents of the stackn");

if (head != NULL)

{

stack_reverse(&head, &(head->next));

}

printf("nThe contents in stack after reversaln");

display(head);

delete(&head);

return 0;

}

void stack_reverse(struct node **head, struct node **head_next)

{

struct node *temp;

if (*head_next != NULL)

{

temp = (*head_next)->next;

(*head_next)->next = (*head);

*head = *head_next;

*head_next = temp;

stack_reverse(head, head_next);

}

}

void display(struct node *head)

{

if (head != NULL)

{

printf("%d  ", head->a);

display(head->next);

}

}

void generate(struct node **head)

{

int num, i;

struct node *temp;

printf("Enter length of list: ");

scanf("%d", &num);

for (i = num; i > 0; i--)

{

temp = (struct node *)malloc(sizeof(struct node));

temp->a = i;

if (*head == NULL)

{

*head = temp;

(*head)->next = NULL;

}

else

{

temp->next = *head;

*head = temp;

}

}

}

void delete(struct node **head)

{

struct node *temp;

while (*head != NULL)

{

temp = *head;

*head = (*head)->next;

free(temp);

}

}

9.) Linear Search Implementation in C

This is an abstract source code of Linear search utility in C. This could be used along in the Turbo C compiler. Others were specifically not tested and not recommended.

#include

int main()
{
int array[100], search, c, n;

printf("Enter the number of elements in arrayn");
scanf("%d",&n);

printf("Enter %d integer(s)n", n);

for (c = 0; c < n; c++)
scanf("%d", &array[c]);

printf("Enter the number to searchn");
scanf("%d", &search);

for (c = 0; c < n; c++)
{
if (array[c] == search)     /* if required element found */
{
printf("%d is present at location %d.n", search, c+1);
break;
}
}
if (c == n)
printf("%d is not present in array.n", search);

return 0;
}

10.) Binary Search using Arrays

The source code below is the implementation of binary search algorithm in C using arrays.

#include
int main(){

int a[10],i,n,m,c=0,l,u,mid;

printf("Enter the size of an array: ");
scanf("%d",&n);

printf("Enter the elements in ascending order: ");
for(i=0;i<n;i++){
scanf("%d",&a[i]);
}

printf("Enter the number to be search: ");
scanf("%d",&m);

l=0,u=n-1;
while(l<=u){
mid=(l+u)/2;
if(m==a[mid]){
c=1;
break;
}
else if(m<a[mid]){
u=mid-1;
}
else
l=mid+1;
}
if(c==0)
printf("The number is not found.");
else
printf("The number is found.");

return 0;
}

11.) Insertion Sort Implementation in C using Arrays.

This is insertion sort in C using Arrays. The source code is available below:

#include

int main()
{
int n, array[1000], c, d, t;

printf("Enter number of elementsn");
scanf("%d", &n);

printf("Enter %d integersn", n);

for (c = 0; c < n; c++) {
scanf("%d", &array[c]);
}

for (c = 1 ; c <= n - 1; c++) { d = c; while ( d > 0 && array[d] < array[d-1]) {
t          = array[d];
array[d]   = array[d-1];
array[d-1] = t;

d--;
}
}

printf("Sorted list in ascending order:n");

for (c = 0; c <= n - 1; c++) {
printf("%dn", array[c]);
}

return 0;
}

12.) Merge Sort in C using Arrays

Here is the source code for Merge sort in C using Arrays:

#include
#define MAX 50

void mergeSort(int arr[],int low,int mid,int high);
void partition(int arr[],int low,int high);

int main(){

int merge[MAX],i,n;

printf("Enter the total number of elements: ");
scanf("%d",&n);

printf("Enter the elements which to be sort: ");
for(i=0;i<n;i++){
scanf("%d",&merge[i]);
}

partition(merge,0,n-1);

printf("After merge sorting elements are: ");
for(i=0;i<n;i++){
printf("%d ",merge[i]);
}

return 0;
}

void partition(int arr[],int low,int high){

int mid;

if(low<high){
mid=(low+high)/2;
partition(arr,low,mid);
partition(arr,mid+1,high);
mergeSort(arr,low,mid,high);
}
}

void mergeSort(int arr[],int low,int mid,int high){

int i,m,k,l,temp[MAX];

l=low;
i=low;
m=mid+1;

while((l<=mid)&&(m<=high)){

if(arr[l]<=arr[m]){ temp[i]=arr[l]; l++; } else{ temp[i]=arr[m]; m++; } i++; } if(l>mid){
for(k=m;k<=high;k++){
temp[i]=arr[k];
i++;
}
}
else{
for(k=l;k<=mid;k++){
temp[i]=arr[k];
i++;
}
}

for(k=low;k<=high;k++){
arr[k]=temp[k];
}
}

13.) Quick Sort Implementation in C using Arrays

Below is the raw source code for Quick Sort implementation in C using Arrays:

#include

void quicksort(int [10],int,int);

int main(){
int x[20],size,i;

printf("Enter size of the array: ");
scanf("%d",&size);

printf("Enter %d elements: ",size);
for(i=0;i<size;i++)
scanf("%d",&x[i]);

quicksort(x,0,size-1);

printf("Sorted elements: ");
for(i=0;i<size;i++)
printf(" %d",x[i]);

return 0;
}

void quicksort(int x[10],int first,int last){
int pivot,j,temp,i;

if(first<last){
pivot=first;
i=first;
j=last;

while(i<j){
while(x[i]<=x[pivot]&&i<last) i++; while(x[j]>x[pivot])
j--;
if(i<j){
temp=x[i];
x[i]=x[j];
x[j]=temp;
}
}

temp=x[pivot];
x[pivot]=x[j];
x[j]=temp;
quicksort(x,first,j-1);
quicksort(x,j+1,last);

}
}

14.) Heap Sort Implementation in C using Arrays

Below is the source code for Heap Sort in C using Arrays:

#include
void main()

{

int heap[10], no, i, j, c, root, temp;

printf("n Enter no of elements :");

scanf("%d", &no);

printf("n Enter the nos : ");

for (i = 0; i < no; i++)

scanf("%d", &heap[i]);

for (i = 1; i < no; i++)

{

c = i;

do

{

root = (c - 1) / 2;

if (heap[root] < heap[c])   /* to create MAX heap array */

{

temp = heap[root];

heap[root] = heap[c];

heap[c] = temp;

}

c = root;

} while (c != 0);

}

printf("Heap array : ");

for (i = 0; i < no; i++) printf("%dt ", heap[i]); for (j = no - 1; j >= 0; j--)

{

temp = heap[0];

heap[0] = heap[j    /* swap max element with rightmost leaf element */

heap[j] = temp;

root = 0;

do

{

c = 2 * root + 1;    /* left node of root element */

if ((heap[c] < heap[c + 1]) && c < j-1)

c++;

if (heap[root]<heap[c] && c<j)    /* again rearrange to max heap array */

{

temp = heap[root];

heap[root] = heap[c];

heap[c] = temp;

}

root = c;

} while (c < j);

}

printf("n The sorted array is : ");

for (i = 0; i < no; i++)

printf("t %d", heap[i]);

printf("n Complexity : n Best case = Avg case = Worst case = O(n logn) n");

}

15.) Bubble Sort Implementation in C using Arrays

Below is the source code for bubble sort in C using Arrays:

#include

int main()
{
int array[100], n, c, d, swap;

printf("Enter number of elementsn");
scanf("%d", &n);

printf("Enter %d integersn", n);

for (c = 0; c < n; c++)
scanf("%d", &array[c]);

for (c = 0 ; c < ( n - 1 ); c++)
{
for (d = 0 ; d < n - c - 1; d++) { if (array[d] > array[d+1]) /* For decreasing order use < */
{
swap       = array[d];
array[d]   = array[d+1];
array[d+1] = swap;
}
}
}

printf("Sorted list in ascending order:n");

for ( c = 0 ; c < n ; c++ )
printf("%dn", array[c]);

return 0;
}

3. Operating System – CPU Management

CPU Management – A step towards Process Management

 

By Shritam Bhowmick
Web Application Penetration Tester
LinkedIn: https://www.linkedin.com/profile/view?id=281014248&trk=nav_responsive_tab_profile
Academia: https://independent.academia.edu/ShritamBhowmick
Facebook: https://www.facebook.com/coded32

Last post, I talked about the coverage of the series on operating system and the introductory post with the importance of operating system, as well as defining the operating system. In this post, I’d discuss CPU management and hence go closer into process management. The CPU is known by Central Processing Unit and it is hence obvious CPU is a process manager of the computer system. It processes the given data into desired output which is useful for the user. The process which takes place in the CPU should be in the main memory, that is the data which is to be executed via processing should be in the main memory (Random Access Memory or RAM).  A multi-user system uses processes, and a process does not mean a multiple CPU handling these processes, it means that the processes are handled by the same CPU but with optimization in time and processing efficiency. The data provided by the user is fed to the CPU which is a ‘Job’, this Job needs processing to be done and hence result in execution in the CPU, the Jobs require the dependency data to be present in the main memory. Jobs are the tasks which the CPU has to undertake in order to process them, and then execute and write the results to the secondary devices (special I/O devices as discussed in y previous posts) or directly as a output to a video terminal, or printer, etc.

The terms which would be required for CPU management are:

  1. Waiting Time
  2. Turnaround Time

What is Waiting Time?

The gap in time between the given job for execution to the CPU and the actual time when the CPU begins to execute the given job is known as the waiting time. Or in other words the time the processing for the given job to be executed/processed remains in the ready queue for the CPU to begin processing or executing is termed as the waiting time.

Let t(0) be the time the user has given a certain job for processing or execution to the CPU. And let the actual time when the CPU begins processing/executing the given job be t(i). The time difference between t(i) and t(0) i.e: t(i) – t(0) = t(w) {Waiting time} is termed as the waiting time. So the equations are:

T(i) - T(0) = T(w)

Where,

  1. T(i) = Time at which the user had supplied the job for processing or execution to the CPU.
  2. T(0) = Time at which the CPU actually starts processing or execution of the supplied job.
  3. T(w) = Waiting Time.

Now for the CPU to give an output, there must be some time taken by the CPU in order to process the job. This time on a timeline of the whole processing from job given, to job initialization by the CPU and the output could be shown as below:

 

Waiting Time Demonstration

 

As shown, the processed job by the CPU is at the last entry which is marked as T (p), this would be the output time stamp when the job is done by the CPU.  Now, the concept of turnaround time hops in.

What is Turnaround Time?

The time taken for a job to complete it’s processing or execution from the point of the job submission to the CPU until it’s processing has been completed is termed as turnaround time. Or in other words, turnaround time is the total time taken between the submission of a program/process/thread/task  for execution and the return of the complete output to the user.

Now, as we had assumed the time stamp when the job is completed to be T (p), the turnaround time would be as following described by the equation:


T (t) = T (p) - T (0)

Where,

  1. T (t) = Turnaround Time
  2. T (p) = Processed or executed job by the CPU returned to the user or written in the special I/O device or outputted.
  3. T (0) = The time stamp when the user submitted the job/task to the CPU.

Diagrammatically, it would be:

Turnover Time

Having said that, the users would always want the waiting time and the turnaround time to be minimum in order to accomplish processing and outputting of the given jobs. But the CPU handles multi-jobs simultaneously and hence this isn’t possible or realistic. Jobs should be executed in first come first served (FCFS) basis and hence certain waiting time has to be allotted to the incoming jobs. Let’s assign these incoming jobs to be:

J1, J2, J3, J4 which would be incoming from ascending order, i.e: 1st J1 is fed to the CPU, then J2, J3 and finally J4. Hence the processing by the CPU should also be in accordance. That is if FCFS (First Come First Served) method is applied, J1 should be undertaken first and then the rest and hence the processing of J1 will be first then the rest. Applying that:

J1 = 15 time units of execution.
J2 = 8 time units of execution.
J3 = 10 time units of execution.
J4 = 3 time units of execution.

The jobs have been assigned with there respective time units of execution, that is each job is actually undertaken by the CPU at a certain time lapse, which until then it’s a waiting time. Assuming the jobs have arrived to the CPU progressively as J1, J2, J3 and then J4, I draw a general timeline:

 

Calculate Average Waiting Time

 

The above diagram shows the calculation part of the average job wait time. The calculation is simple, ignore the numbers and because it’s FCFS, start from ‘0’ for the Job 1 since Job 1 never waited, the others were in queue. The numbers given are for execution time that is the time interval the job took to get over with execution and hence the waiting time for each would be calculated as:

W (j1) = 0
W (j2) = 0 + 15 = 15
W (j3) = 15 + 8 = 23
W (j4) = 23 + 10 = 33


Total Wait time = 71
______________

The last 3 units of time wasn’t a wait time, it was the time taken for the 4th job to get over with execution, the 4th job already waited for 33 units of time for it’s turn to get execution scheduled. This process undertaken by the CPU is called Job Scheduling or simply Scheduling. That comes deep later, but to calculate the average waiting time, I need to consider all the jobs which are 4 items so:

71/4 = 17.75 is the average waiting time i.e: T (wa). Hence, T (Wa) = 17.75 time units for the above example on wait time average. Now, changing the sequential order of the incoming jobs. The CPU has no control over the incoming of the jobs, but what the CPU has control of is the order in which the jobs will be given a priority for execution. This could be decided by the CPU. So, consider the order below for jobs: (considering the same queue of jobs, the situation here is re-scheduling the jobs

J4 = 3 units of time
J2 = 8 units of time
J3 = 10 units of time
J1 = 15 units of time

In this case, the execution time remains the same, however the jobs are re-shuffled according to the CPU’s preference and the priority in taking up the job. Previously, the jobs were taken first come first served basis, but here even though the jobs arrived sequentially, the CPU has the authority and control of the execution land the processing of the jobs which were given by the user. The CPU decides to execute the job in the order such that J4 was executed first, next was J2, and then J3 and finally J4 was executed.

Considering the above situation, I now wanted to determine the average waiting time for such a schedule prescribed by the CPU because the CPU has the control on the scheduling part but does not have the control over the incoming jobs. To draw a rough sketch of just occurrences with a job execution and waiting timeline:

 

Scheduling without FCFS. Rescheduling with CPU’s control over Scheduling

 

Considering the image below I had drawn (MS paint, mind not!), the time taken for execution of the jobs in previous scenario were the same, but the scheduling was done by the CPU without FCFS method but taking in priority to which jobs has to be executed first to perform optimization. The magic happens here. Now if we calculate the waiting time:

W (J4) = 0 (since it arrived first)
W (J2) = 0 + 3 = 3 (since J2 had to wait for 3 units of time because 3 units of time were wasted {rather not!} in execution of job J4)
W (J3) = 3 + 8 = 11 (since J3 had to wait until J2 was finished executing with time lapse of 8 units)
W (J1) = 11 + 10 = 21 (since J1 had to wait for J3 to finish up with execution with time lapse of 10 units)

Hence;

W (J4) = 0
W (J2) = 3
W (J3) = 11
W (J1) = 21


Total Wait Time = 35 time units
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Now, if I calculate the average waiting time T (Wa) for this, that is 35/4, it comes to 8.75 time units. So:

T (Wa) = 8.75

which is far lesser in waiting time than the previous scenario. Calculating the optimization which had occurred here and the difference, our previous FCFS achieved 17.75 of waiting time, and this scheduling by the CPU achieved 8.75. The difference in wait time optimization being:

17.75 - 8.75 = 9.00 time units

A budget of total 9 time units.  So we find that just by changing the order, the same jobs were optimized. The average waiting time were reduced drastically so naturally the CPU would now prefer the second type of scheduling rather than the first scheduling. The user wold always prefer the first scenario but the CPU won’t allow that because it has to follow optimization rules. In the second scenario, there is a pattern why the average waiting time were drastically reduced. This is achieved by executing the jobs first which take lesser time for execution because the next queue of jobs will have to ‘wait’ lesser and hence optimization could occur.There are various objectives which could be achieved, the objective achieved here was to minimize the average waiting time for the jobs together to be finished in an optimized way.

So that’d be the very touch towards process management in this post. Next post, I’d bring some more fruits to the blog. The concepts of process management is vast and does not end with this basic post.  To keep updated if you like these posts, subscribe via mail or keep visiting the blog. Cheers out!