Assignment 2 Programming Exercise Stack In the stack example

Assignment 2 Programming Exercise (Stack) In the stack example program, add a method called search(char item) that performs searching algorithm on a stack. To search for an item in a stack, the searched item can only be compared with the item on the top of the stack. If the item on the top of the stack is NOT the searched item, it must be popped off the stack so that the item underneath it can be used to compare with the searched item. After the searching is done, the removed item(s) must be pushed back to the stack to remain original stack again. Sample method\'s calls in main and its output int main) push(\'H\') H is added to the top of the stack push(\'A): push(\'T\') displayStack)i isplay stack is added to the top of the stack T is added to the top of the stack Display Stack search(\'HD displayStack) cout

Solution

#include<stdio.h>
#include<process.h>
#include<stdlib.h>
//To count number of items in the stack
int count = 0;
//Declaration of stack
struct mystack
{
char data; //To store data
struct mystack *next; //Self referencial pointer
}*top = NULL;
typedef struct mystack st;
//Push a data
void push(char ch)
{
st *p;
//Dynamically allocates memory
p = (st *) malloc(sizeof(st));
p -> data = ch;
p -> next = top;
top = p;
count++; //Counter increased
printf(\"\ %c is added to the top of the stack \", p -> data);
}
//Pops an data
int pop( )
{
st *p;   p = top;
//Checks underflow condition
if(top == NULL)
    printf(\"\ Stack Underflow\");
else
{
    top = top -> next;
    count--;
return (p -> data);
}
}
//Display the stack data
void displayStack()
{
st *p;   p = top;
printf(\"\ Display Stack\");
//Loops till end of stack
while(p != NULL)
{
   printf(\"\ Data = %c\", p -> data);
p = p -> next;
}
printf(\"\ ----------------------------\");
}
//Search for an item in the stack
void search(char item)
{
//Dynamically allocates memory to temp to store removed items
char *temp = (char *) malloc(count * sizeof(char));
//To keep track how many items removed from the stack
int i = 0, j;
st *p;   p = top;
printf(\"\ ********* Begin to search for %c ********** \ \", item);
//Loops till end of the stack
//Search for the item if found come out of the loop
//If not found add it to the temporary array and delete it from the stack
while(p != NULL)
{
   if(p -> data == item)
{
printf(\"\ %c is now found at the top of the stack. \ \", item);
break;
}
else
{
printf(\"\ %c is not at the top of the stack. \ \", item);
*(temp + i) = pop();
p = p -> next;
i++;
}
displayStack();
}
//Adds the removed data back to the stack
for(j = i - 1; j >= 0; j--)
{
printf(\"\ %c needs to be added back to the stack.\", temp[j]);
push(temp[j]);
}
displayStack();
}
void main( )
{
int choice, item;
push(\'H\');
push(\'A\');
push(\'T\');
displayStack();
search(\'H\');
}

Output:

H is added to the top of the stack
A is added to the top of the stack
T is added to the top of the stack
Display Stack
Data = T
Data = A
Data = H
----------------------------
********* Begin to search for H **********

H is not at the top of the stack.

Display Stack
Data = A
Data = H
----------------------------
H is not at the top of the stack.

Display Stack
Data = H
----------------------------
H is now found at the top of the stack.

A needs to be added back to the stack.
A is added to the top of the stack
T needs to be added back to the stack.
T is added to the top of the stack
Display Stack
Data = T
Data = A
Data = H
----------------------------