Example: Palindrome Check using Two Pointers in C

// Palindrome Check using Two Pointers
#include <stdio.h>
#include <string.h> // Required for strlen()

// Function to check if a string is a palindrome
// Returns 1 if palindrome, 0 otherwise
int isPalindromeTwoPointers(const char *str) {
    // Step 1: Handle null or empty string
    if (str == NULL || strlen(str) == 0) {
        return 1; // Empty string is considered a palindrome
    }

    // Step 2: Initialize two pointers
    int left = 0;
    int right = strlen(str) - 1;

    // Step 3: Iterate while left pointer is less than right pointer
    while (left < right) {
        // Step 4: Compare characters at current pointers
        if (str[left] != str[right]) {
            return 0; // Mismatch found, not a palindrome
        }
        // Step 5: Move pointers towards the center
        left++;
        right--;
    }

    // Step 6: If loop completes, string is a palindrome
    return 1;
}

int main() {
    char str1[] = "madam";
    char str2[] = "racecar";
    char str3[] = "hello";
    char str4[] = ""; // Empty string
    char str5[] = "a"; // Single character string
    char str6[] = "Madam"; // Case sensitive example

    printf("'%s' is a palindrome: %d\n", str1, isPalindromeTwoPointers(str1));
    printf("'%s' is a palindrome: %d\n", str2, isPalindromeTwoPointers(str2));
    printf("'%s' is a palindrome: %d\n", str3, isPalindromeTwoPointers(str3));
    printf("'%s' is a palindrome: %d\n", str4, isPalindromeTwoPointers(str4));
    printf("'%s' is a palindrome: %d\n", str5, isPalindromeTwoPointers(str5));
    printf("'%s' is a palindrome: %d\n", str6, isPalindromeTwoPointers(str6)); // Will be 0 due to case sensitivity

    return 0;
}