Question

#19

19. A palindrome is a string that can be read backward and forward with the same result. For example, the following is a palindrome: Able was I ere I saw Elba.

with the following instructions

Answer 1

SOURCE CODE IN C:

stack.h

#include <stdlib.h>

#define MAX_SIZE 1000

struct stack

{

char characters[MAX_SIZE];

int size;

};

struct stack* create()

{

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

st->size=0;

return st;

}

void push(struct stack *st, char c)

{

if(st->size==MAX_SIZE)

return;

st->characters[st->size]=c;

st->size+=1;

}

char pop(struct stack *st)

{

if(st->size==MAX_SIZE)

return '\0';

char data=st->characters[st->size-1];

st->size-=1;

return data;

}

main.c

#include <stdio.h>

#include "stack.h"

#include <string.h>

#include <ctype.h>

int main(void)

{

char str[1000];

printf("Enter the sentence: ");

fgets(str, 1000, stdin);

struct stack *st=create();

char original[1000]="";

for(int i=0; i<strlen(str)-1; i++)

{

char ch=tolower(str[i]);

if(ch>='a' && ch<='z')

{

strncat(original, &ch, 1);

push(st, ch);

}

}

char reverse[1000]="";

for(int i=0; i<strlen(str)-1; i++)

{

char ch=pop(st);

strncat(reverse, &ch, 1);

}

if(strcmp(reverse, original)==0)

printf("It is a palindrome!\n");

else

printf("It is not a palindrome!\n");

return 0;

}

OUTPUT:

Enter the sentence: Madam, I'm Adam It is a palindrome!

Regards!