Hello here is java code to change Infix expression to PostFix expression. infix expression is the expression we understand and do algebraic manipulation using BODMAS rule. Compilers uses PostFix expression to do calculation. Here we would make use of the stack we discussed in the previous articles.

If you are beginner in Java. The block at 10 - 13 is a initialization block.
Using constructor we set the max Size and the size of array to of that maxSize.
The core of this code is the method inToPostFix() Here we could explain the Algorithm in words

  1. Initialize the empty stack.(astack[])
  2. Scan each character of the given infix expression from left to right. (theExpression.charAt(i))
  3. If the scanner Character is an Operand then add it to post fix string (theFinalExpression)
  4. If the scanned character is an operator then
    1. If the stack is empty, push the scanner operator int the stack.
    2. If the stack is not empty then compare the precedence of the operator at the top of the stack. If the precedence of scanned is less then or equal to the precedence of operator at TOS, then pop TOS and add it to postfix string and push the scanned operator into the TOS. If the precedence of the scanned operator is higher then the operator at TOS then push operator to the stack.
  5. If the scanned character is opening parenthesis then push it on to the stack and continue the above process steps until closing parenthesis is not scanned. When we get closed parenthesis then pop the operators from the stack until we reach opening parenthesis and then pop opening parenthesis from stack.
  6. The process is continued until all the characters of infix expression are scanned. and pop all the remaining operators from stack and add them in to the postfix string in the way they pop out.
Here is the code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
import java.util.Scanner;
class InToPostFix
{
 int maxSize;
 char astack[];
 int TOS;
 String theFinalExpression;
 String theExpression;
 
 {
  TOS = -1;
  theFinalExpression = "";
 }
 
 InToPostFix(int maxSize, String theExpression)
 {
  this.maxSize = maxSize;
  this.astack = new char [maxSize];
  this.theExpression = theExpression;
 }

 void inToPostFix()
 {
  for(int i = 0; i< maxSize ;i++)
  {
   char element = theExpression.charAt(i);
   if(isOperand(element))
    theFinalExpression = theFinalExpression + element;
   else if(isOperator(element))
   {
    if(stackIsEmpty())
     push(element);
    else
    {
     int a;
     a = checkThePrecedence(element);
     if(a == 3) // element is of higher precedence:w
      push(element);
     else if(astack[TOS] != '(')
     {
      char operator = pop();
      theFinalExpression = theFinalExpression + operator;
      push (element);
     }
    }
   }
   else if(element == '(')
    push(element);
   else if(element == ')')
   {
    char temp;
    while(astack[TOS] != '(')
    {
     temp = pop();
     theFinalExpression = theFinalExpression + temp;
    }
    pop();// Remove the '(' from stack
   }
  }
  //while(!(stackisEmpty())):q
  while(TOS != -1)
  {
   char temp = pop();
   theFinalExpression = theFinalExpression + temp;
  }
 }

 char pop()
 {
  char item = astack[TOS];
  TOS -= 1;
  return item;
 }
 
 int checkThePrecedence(char element)
 {
  char item = astack[TOS];
  int assign, assign2;
  if (item == '$')
   assign = 3;
  else if (item == '*' || item == '/')
   assign = 2;
  else //(item == '+' || item == '-')
   assign = 1;
  if (element == '$')
   assign2 = 3;
  else if(element == '*' || element == '/')
   assign2 = 2;
  else //(element == '+' || element == '-')
   assign2 = 1;
  if(assign2 > assign)
   return 3; // element is of higher precedence
  else if(assign2 == assign)
   return 2; // element is in same as in stack
  else //(assign2 < assign)
   return 1; // element is of lower precedence
 }

 boolean stackIsFull()
 {
  if(TOS == maxSize - 1)
   return true;
  else
   return false;
 }

 boolean stackIsEmpty()
 {
  if(TOS == - 1)
   return true;
  else
   return false;
 }
 
 void push(char element)
 {
  TOS += 1;
  astack[TOS] = element;
 }
 
 static boolean isOperand(char element)
 {
  if((element >='a' && element <='z') || (element >='A' && element <='Z'))
   return true;
  else
   return false;
 }
 
        static boolean isOperator(char element)
        {
                if(element == '+' || element == '-' || element == '*' || element == '/' || element == '$')
                        return true;
                else
                        return false;
        }

 void displayFinal()
 {
  System.out.println("The Final Exptession is:-\n" + theFinalExpression);
 }

 public static void main(String []args)
 {
  Scanner input = new Scanner(System.in);
  Scanner input2 = new Scanner(System.in);
  System.out.println("Enter the InFix expression");
  String theExpression = input.nextLine();
  int maxSize = theExpression.length();
  InToPostFix inToPostFix = new InToPostFix(maxSize, theExpression);
  inToPostFix.inToPostFix();
  inToPostFix.displayFinal();
  int option;
  int next = 1;
  while(next == 1)
  {
   System.out.println("Option:- \tTo do:\n1\tConvert another expression\n2\tExit this program");
   option = input2.nextInt();
   switch(option)
   {
    case 1:
    {
     System.out.println("Enter the InFix expression");
     theExpression = input.nextLine();
     maxSize = theExpression.length();
     InToPostFix inToPostFixOb = new InToPostFix(maxSize, theExpression);
     inToPostFixOb.inToPostFix();
     inToPostFixOb.displayFinal();
     break;
    }
    case 2:
    {
     next = 0;
     System.out.println("Thank you:)");
     break;
    }
    default:
     System.out.println("Please Enter a valid option");
   }
  }
 }
}

Here we use $ for power operation. Power has the highest precedence. We use while loop in the main function and switch case to match the options you selected and call the selected methods. If I need to explain any of the code above I will always be available in the comment section. Thank you!
Hello here is Circular Queue. Here we create two separate file for the class and the main method. Everything is simple and common code here. I would like to introduce a new style to initialize a instance variables. The code block from line no 7 to line no 10 on CircularQueue.java is a Initialization Block. The benefit of creating any initializing block is that every constructors on the class would use the block to initialize variables. To initialize the static variables we just use static keyword before the block.

Here is CircularQueue.java file.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
class CircularQueue
{
 int maxSize;
 int rear;
 int front;
 int aQueue[];
 {
  rear = -1;
  front = -1;
 }
 CircularQueue(int maxSize)
 {
  this.maxSize = maxSize;
  this.aQueue = new int[maxSize];
 }
 void enQueue(int item)
 {
  if(((rear+1) % maxSize) == front)
  {
   System.out.println("Queue is Full");
  }
  else
  {
   if (rear == front && front == -1)
   {
    front += 1;
   }
   rear = (rear+1) % maxSize;
   aQueue[rear] = item;
  }
 }
 void deQueue()
 {
  if(rear == front && rear == -1)
  {
   System.out.println("Queue is Empty.");
  }
  else
  {
   int item = aQueue[front];
   if(rear == front)
   {
    rear = -1;
    front = -1;
   }
   else
   {
    front = (front + 1) % maxSize;
   }
   System.out.println(item + " is deQueued from the Queue");
  }
 }
 
 String elementOrElements()
 {
  String send = (rear == front)? (" ") :("s ");
  return send;
 }
  
 void display()
 {
  int tmpfront = front;
  if(rear == front && rear == -1)
                {
                        System.out.println("Queue is Empty.");
                }
                else
  {
   System.out.println("The element"+ elementOrElements() + "on the Queue are:- ");
   for(int i=0; i<maxSize ; i++)
   {
    if(tmpfront != rear)
    {
     System.out.println(aQueue[tmpfront]);
     tmpfront = (tmpfront + 1) % maxSize;
    }
    else
    {
     System.out.println(aQueue[rear]);
     break;
    }
   }
  }
 }
}

And Here is CircularQueueTest.java file.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

import java.util.Scanner;
public class CircularQueueTest
{
 public static void main(String []args)
 {
  Scanner input = new Scanner(System.in);
  System.out.print("Enter total no of elements to be in the queue:- ");
  int maxSize = input.nextInt();
  CircularQueue queue = new CircularQueue(maxSize);
  int select;
  int term = 0;
  while (term == 0)
  {
   System.out.print("\nOption:\tTo Do:\n1\tTo push element.\n2\tTo POP element.\n3\tTo Display the Queue elements.\n4\tTo Exit the Program.\nEnter your option:- ");
                 select = input.nextInt(); 
   switch(select)
   {
    case 1:
    {
     System.out.print("Enter element to insert in the Queue:- ");
     int ele = input.nextInt();
     queue.enQueue(ele); 
     break;
    }
    case 2:
    {
     queue.deQueue();
     break;
    }
    case 3:
    {
     queue.display();
     break;
    }
    case 4:
    {
     term = 1;
     System.out.println("Thank you!");
     break;
    }
    default:
     System.out.println("Enter a valid options");
   }
  }
 }
}

To fully understand this code you need to figure out what actually (front + 1) % maxSize do. Take your time and do some calculation. It would be better if calculate it and figure out it by yourself.

Hint:- (front + 1) % maxSize and (rear+1) % maxSize will always return 0 or < maxSize.
Hello Today we are here with a code of Stack Implementation using Array. We had already discussed about stack. Here we use 3 methods
1. To Push the elements
2. To POP the element
3. To display the elements on the stack.

This is no complex code. What we need to remember is that we should initialize TOS as -1 initially. Most beginner users could face error on the 6th and 11th line of code. Here at first we first create a reference variable at line 6 and  create required length array in line 11.
If we use int aarray = new int[MaxSize]; in the class, it will create a zero-length array. as int MaxSize; means int MaxSize = 0;

Other are really simple algorithms. we need to check if Stack is full while pushing and need to check if stack is empty while using pop.

We need to increment TOS everytime we push a element and decrement whenever we pop a element.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
import java.util.Scanner;
class Stack
{
 int TOS = -1;
 int MaxSize;
 int aarray[];
 
 Stack(int Max1Size)
 {
  this.MaxSize = MaxSize;
  this.aarray = new int[MaxSize];
 }
 void push(int a)
 {
  if(TOS == MaxSize - 1)
  {
   System.out.println("Stack is Full");
  }
  else
  {
   TOS += 1;
   aarray[TOS] = a;
   System.out.println(a +" is inserted in the Stack");
  }
  return;
  
 }
 void pop()
 {
  if (TOS == -1)
  {
   System.out.println("Stack is Empty.");
  }
  else
  {
   int item = aarray[TOS];
   TOS -= 1;
   System.out.println(item +" is poped Out from the Stack");
  }
  return;
 }
 void display()
 {
  if (TOS == -1)
  {
   System.out.println("Stack is Empty.");
  }
  else
  {
   System.out.println("Elements in Stack are:- ");
   for(int i = TOS; i >= 0; i--)
   {
    System.out.println(aarray[i]);
   }
  }
  return;
 }
}
public class StackTest
{
 public static void main(String args[])
 {
  Scanner input = new Scanner(System.in);
  System.out.println("Enter Maximum size of array");
  int MaxSize = input.nextInt();
  Stack astack = new Stack(MaxSize);
  int next = 0;
  while( next == 0)
  {
   System.out.println("\nOption:- \t To Do\n1 \t Push to stack. \n2 \t Pop from stack\n3 \t Display stack \n4 \t Exit the program");
   int select = input.nextInt();
   switch(select)
   {
    case 1:
     {
      System.out.println("Enter the element to push in the stack");
      int element = input.nextInt();
      astack.push(element);
      break;
     }
    case 2:
     {
      astack.pop();
      break;
     }
    case 3:
     {
      astack.display();
      break;
     }
    case 4:
     {
      next = 1;
      System.out.println("Thank You! :)");
      break;
     }
    default:
     {
      System.out.println("Please Enter a valid OPtion.");
      break;
     }
   }
  }
 }
}

This one of the code I had written at college in practical of DSA. Thank you :)
Please Follow How to Create Facebook Friends Day Video.
Today is facebook 14th Birthday. On that occasion facebook allow users to share video with friends. Sharing what they think about them. You can also share the facebook friends day video. There are a lots of options (award) to give to friends All of them are predefined, Facebook will create a short video for your friends. You could publish it on his/her timeline or can send him/her a private message.


History of Facebook?

On February 4, 2004, Mark Zuckerberg launched “Thefacebook”, originally located at thefacebook.com. In 2005, the company dropped “the” from its name after purchasing the domain name facebook.com for US$200,000 The domain facebook.com belonged to AboutFace Corporation before the purchase.

Mark Zuckerberg mention that he had made a lots of mistakes during the development of facebook. He mention "I’ve made dozens of technical errors and bad deals.", He also "I’m proud of what we do and grateful to be a part of something so meaningful." Facebook said there are a lots of path to go and they will work on to Improve Facebook.

Make Facebook Friends Day Video

We had already published this on Time and Update but due to some Server Error we could not serve that page. The Title is How to Create Facebook Friends Day Video.

You can make Facebook Friends Day Video just by following this link. facebook.com/friendsday. Then click in the Create options, Now select a friend and award a option that suits best. Now you can Click in next and confirm whether to send via message or Publish on his Timeline. Conform the process. You can also follow this video Guide.
      

Now it would take some time (about 30 secs ) for your video to be prepared, Then your friend and you can access that video if it was sent of message. If you posted on friends Profile it would be available to public to view.

Most Selected Awards in Facebook Friends Day

Facebook announced that they also celebrate the friends day and they will update the most selected awards among the facebook. Here is the most selected awards till now. There may be alter in ranking of the most selected awards. You can always find that on the friends day page.

Please do comment which of the award you give to most of your friends. I would select the 3rd one to my Friends as they always have my back when I don't have.
Copyright 1998 - 2108 Computer Science and Information Technology