Question

Write a C Program that asks the user to input a string and then the user is prompted back whether the input string is a “Palindrome Word” or not. (A Palindrome Word reads the same backward or forward, eg. madam, racecar, etc.)

Your program should contain a function that accepts the input string from the main function and returns a value indicating whether the input string is a Palindrome or not.

Use Pointers to traverse the string.

Answer 1

#include<stdio.h>

#include<string.h>

#include<stdbool.h>

bool isPalindrome(char str[])

{

    // point to the starting character

    char *start = str;

   

    // point to the ending character

    char *end = str + ( strlen(str) - 1 );

   

    // loop untill start pointer is before end pointer

    while( start < end )

    {

        // if the current character from start and end are not equal

        if( *start != *end )

            return false;

           

        // update the pointers

        start++;

        end--;

    }

   

    return true;

}

int main()

{

    char str[100];

   

    printf("Enter a string : ");

   

    // read complete line

    gets(str);

   

    // if it is palindrome

    if( isPalindrome(str) )

        printf("it is palindrome.");

    // if it is not palindrome

    else

        printf("it is not palindrome.");

   

    return 0;

}

Sample Output

it is palindrome