Question

Problem 1: (Palindromes) A palindrome is a string that's spelled the same way forward and backward. Some examples of palindromes are; radar, able was i ere i saw elba; and, if you ignore blanks, a man a plan a canal panama .Write a recursive function testPa1indrome that returns 1 if the string stored in the array is a palindrome and 0 otherwise. The function should ignore spaces and punctuation in the string.

Please I need it in C program and with comments on it.

Answer 1

/*
 *  C Program to check if a string is palindrome
 */

#include <stdio.h>
#include <string.h>

//  Function to remove punctutations  
void removePunctutations(char str[])
{
  int i, j;

  for(i = 0; str[i] != '\0'; ++i)
  {
    while (!((str[i] >= 'a' && str[i] <= 'z') || (str[i] >= 'A' && str[i] <= 'Z') || str[i] == '\0' || str[i] == ' '))
    {
      for(j = i; str[j] != '\0'; ++j)
      {
        str[j] = str[j+1];
      }
      str[j] = '\0';
    }
  }
  //printf("%s", str);
}

//  Function to recursively check for palindrome
int testPa1indrome(char str[], int begins, int ends)
{
  if (strlen(str) == 0)
    return 0;
  
  if (begins == ends)
    return 1;
  else if (begins < ends)
  {
    if (str[begins] == str[ends])
      return testPa1indrome(str, begins+1, ends-1);
    else
      return 0;
  }
  return 0;
}

//  Driver function
int main()
{
  char mystr[100];

  printf("Enter String: ");
  scanf("%[^\n]s", mystr);

  removePunctutations(mystr);

  if (testPa1indrome(mystr, 0, (strlen(mystr) - 1)))
    printf("Palindrome");
  else
    printf("Not Palindrome");

  return 0;
}

/*  Program ends here */