Question

Q.1. Write a C program that determines whether a line entered by a user is a palindrome or not. You must demonstrate it as an application of stack (you may use linked list implementation demonstrated in the class). Hint! Think of the basic property of a stack i.e. LIFO (list-in-first-out).
Q.2. Write a charQueue header file containing all the function headers of following functions:
1- initiateQueue—to initialize a queue 2- enqueue—to add a node at the rear end of the queue 3- dequeue—to remove a node from the front of the queue 4- printQueue—print a queue

and an implementation file implementing these functions for a Queue of chars. Inside your main method, which should be part of your tester file, read a sequence of chars one at a time. Terminate your sequence if user enters the number 0. Remember the difference between a char and an int!
Print the text user entered (that was stored in your Queue as a series of characters) using a while loop. You should loop as long as the Queue is not empty.

Answer 1

#include<stdio.h>
#include<string.h>
#define MAX 50
int top=-1;
char stack[MAX];
void push(char c)
{
   if(top==MAX-1)
   {
       printf("overflow");
   }
   else
   {
       top++;
       stack[top]=c;
   }
}
void pop()
{
   if(top==-1)
   {
       printf("underflow");
   }
   else
   {
       top--;
   }
}
int main()
{
   char str[50];
   int i,front=0;
   printf("enter the string:");
   scanf(" %[^\n]s",str);
   for(i=0;str[i]!='\0';i++)
   {
       push(str[i]);
   }
   for(i=0;i<(strlen(str))/2;i++)
   {
       if(stack[top]==str[i])
       {
           pop();
           front++;
       }
       else
       {
           printf("not palindrome");        //If not equal break the loop no need to check other characters.
           break;
       }
   }
   if(front==strlen(str)/2)
   {
       printf("palindrome");
   }
}

Explanation:

In this i used arrays to implement the stack.To check given string is palindrome or not ,it is enough to check the left half of the string with right half of the string.the top of the element in stack is compared with first element of the string like that we go ..

OUTPUT:

Dev-C++5.2.0.2 File Edit Search View Project Execute Debug Tools CVS Window Help globala) palin.cpp else 25 F 26 CAProgram Files (x86)\Dev-Cpp\Console Pauser.exe top-- 27 enter not palindrome he stringag 28 int main () Process exited normally. Press any key to continue. . 30 char atrr501 31 int i,front-0; printf ("enter the string: ") 32 33 for (1-0:atr [1] !-'\0 ' :1++ ) 35 36 E push (str[i]) 37 38 r (1-0 ; 1< (strlen (str))/2:1++ ) 40 E if (stack [top]-- str [i] ) 41 42 E 43 pop front++: 45 else 46 47 E ("not palindrome") 50 51 52 if (front--strlen (str) /2) 53 F 54 printr("palindrome") 56 8Compiler Resourcesdh Compile Log Debug Find Results Col 33 Sel 0 Done parsing Line 33 Lines: 56 Length: 670 Insert 7:40 AM

Dev-C++5.2.0.2 File Edit Search View Project Execute Debug Tools CVS Window Help globala) palin.cpp else 25 F CAProgram Files (x86Dev-CppiConsolePauser.exe 26 top-- enter the otring:abc ba palindrone 27 28 int main () Preaa anv keut inue . - . - 30 31 char atrr501: int i,front -0; printf ("enter the string:") 32 33 for (1-0:str [1] !-'\0' ; 1++ ) 35 36 E push (stri]) 37 38 r (1-0 ; 1< (strlen (str))/2:1++ ) 40E if (stack [top]-- str [i] ) 41 42 E 43 pop front++: 45 else 46 47 E ("not palindrome") 50 51 52 if (front--strlen (str) /2) 53 F printr("palindrome") 56 8Compiler Resourcesdh Compile Log Debug Find Results Done parsing Line 37 Col 22 Sel 0 Lines: 56 Length: 670 Insert 7:40 AM

Q2.

Header File:

#include<stdio.h>
#define MAX 150
int front,rear;
char Q[MAX];
void initiateQueue() //To initialize the queue
{
   front=-1;
   rear=-1;
}
void Enque(char c) // inserting at rear end
{
   if(rear==MAX-1)
   {
       printf("Overflow");
   }
   else
   {
       rear++;
       Q[rear]=c;
       if(rear==0)
       {
           front=0;
       }
   }
}
void Dequeue() //deleting at front end
{
   if(front==-1||front>rear)
   {
       printf("Underflow");
   }
   else
   {
       printf("deleted character:%c\n\n",Q[front]);
       front++;
   }
}
void printQueue() //Displaying elements
{   int i;
   printf("Displaying queue elements:");
   for(i=front;i<=rear;i++)
   {
       printf("%c",Q[i]);
   }
}

Main.cpp

#include<stdio.h>
#include<string.h>
#include "charQueue.h"
int main()
{
   char str[150];
   int i=0;
   initiateQueue();
   printf("enter sequence of characters:\n");
   while(1)
   {
       scanf("%c",&str[i]);
       if(str[i]=='0')
       {
           break;
       }
       Enque(str[i]);
   }
   i=front;
   while(i<=rear)
   {
       printf("%c",Q[i]);
       i++;
   }
   printf("\n\n");
   Dequeue();
   printQueue();
}

OUTPUT:

Dev-C++5.2.0.2 File Edit Search View Project Execute Debug Tools CVS Window Help globala) palin.cpp charQueue.h main.cpp 4includecstring.h> . #include " charQueue.h" int main SE 3 CAProgram Files (x86) Dev-CppiConsolePauser.exe enter sequence of characters : : [150] int i-0: initiateQueue () 7 printf ("enter sequence of characters:\n" ) 10 while (1) scant ("a", &str [i]); 12 13 if (strli-0' 14 F 15 break de leted character: a Enque (str[i] ) : Displaying queue elemento: 18 19 i=front 20 while (1< -rear) printf("4a",Q[i] ) Proceos Press any key to continue 22 xited normally. 25 1++: 24 25 printf("\n\n") ; printQueue () 28 8Compiler Resourcesdh Compile Log Debug Find Results Sel 0 Line 28 Colk 2 Lines: 28 Length: 387 Insert Autosaved file CUsers SARATH KUMARDesktop Codes\charQueue.h K7 8:24 AM

I have done this code in Dev c++ IDE.

If any doubts comment below...