Palindrome Checking

A palindrome is a sequence of characters or numbers, which reads the same both forward and backward.  Example:   madam, kayak, 12321.

//Program to check palindrome

#include<stdio.h>

#include<conio.h>

main()

{

 int choice,i=0,j,n,num,rev=0;

 char *str;

 clrscr();

 do

 {

  printf("1. String Palindrome\n 2. Number Palindrome\n");

  printf("Enter your choice\n");

  scanf("%d",&choice);

  switch (choice)

  {

    case 1: printf("Enter the string\n");

              scanf("%s",str);

              while (str[++i] !='\0');          // To count the number of characters

                 i=i-1;

              for(j=0;j<=i;j++,i--)             // j starts from first character and i starts from last character

if (str[j]!=str[i])

break;

                if (j>i)

printf("The given string is palindrome\n");

               else

printf("The given string is not palindrome\n");

               break;

    case 2: printf("Enter the number\n");

              scanf("%d",&n);

              num=n;                     //the given number is needed for final comparison; hence stored in num

              rev=0;

             while (n>0)

    {

rev=rev*10+n%10;

n=n/10;

             }

             if (num==rev)

printf("The given number %d is palindrome\n",num);

            else

printf("The given number %d is not palindrome\n",num);

             break;

    default: printf("Wrong choice\n");

   }

   printf("Do you want to continue? 1. Yes  2. No\n");

   scanf("%d",&choice);

 }while (choice==1);

getch();

}

/*

OUTPUT

------------

1

Enter the string

mary

The given string is not palindrome

Do you want to continue? (y/n)1. Yes  2. No

1

1. String Palindrome

2. Number Palindrome

Enter your choice

2

Enter the number

12321

The given number 12321 is palindrome

Do you want to continue? (y/n)1. Yes  2. No

1

1. String Palindrome

2. Number Palindrome

Enter your choice

2

Enter the number

1234

The given number 1234 is not palindrome

Do you want to continue? (y/n)1. Yes  2. No

2

*/