Slip 14 - A) Write a ‘C’ program to accept a string from a user and reverse it using Dynamic implementation of Stack.

Solution:

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <limits.h>

# define MAX 50

struct Stack

{

    int top;

    unsigned size;

    char* array;

};

struct Stack* createStack(unsigned size)

{

    struct Stack* stack = (struct Stack*) malloc(sizeof(struct Stack));

    stack->size = size;

    stack->top = -1;

    stack->array = (char*) malloc(stack->size * sizeof(char));

    return stack;

}

int isFull(struct Stack* stack)

{ return stack->top == stack->size - 1; }

int isEmpty(struct Stack* stack)

{ return stack->top == -1; }

void push(struct Stack* stack, char item)

{

    if (isFull(stack))

        return;

    stack->array[++stack->top] = item;

}

char pop(struct Stack* stack)

{

    if (isEmpty(stack))

        return 0;

    return stack->array[stack->top--];

}

void reverse(char str[])

{

   

    int n = strlen(str);

    struct Stack* stack = createStack(n);

 

    

    int i;

    for (i = 0; i < n; i++)

        push(stack, str[i]);

 

    

    for (i = 0; i < n; i++)

        str[i] = pop(stack);

}

 

int main()

{

int i,len;

    char str[MAX] ;

    

    printf("Enter the string\n");

    scanf("%s",str);

    len=strlen(str);

    for(i=0; i<len; i++)

    {

    reverse(str);

}

    

    printf("Reversed string is %s", str);

 

    return 0;

}