Help thing :)

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <ctype.h>

bool is_alpha(char ch) {
    if((ch >= 97 && ch <= 122) || (ch >= 65 && ch <= 90)) {
        return true;
    }
    return false;
}

size_t getl(char **lineptr)
{
    size_t size = 0;
    char ch;

    while ((ch = getchar()) != '\n' && ch != EOF)
    {
        // allocate it if it's not
        if (!*lineptr) {
            *lineptr = (char*)malloc(sizeof(char));
            size = 1;
        }
        else {
            *lineptr = (char*)realloc(*lineptr, ++size);
        }

        // copy
        (*lineptr)[size - 1] = ch;
    }

    // add null termination if the pointer is not null
    if (*lineptr) {
        // realloc with +1 size
        *lineptr = (char*)realloc(*lineptr, ++size);
        (*lineptr)[size - 1] = '\0';
    }

    return size - 1; // don't count null termination
}

size_t filter_alphabets(char **target, size_t size) {
    char *result = NULL;
    size_t result_size = 0;
    size_t idx = 0;

    while(idx < size) {
        if(is_alpha((*target)[idx])) {
            if(!result) {
                result = (char*)malloc(sizeof(char));
                result_size = 1;
            }
            else {
                // increase buffer size by one
                result = (char*)realloc(result, ++result_size);
            }

            result[result_size - 1] = tolower((*target)[idx]);
        }
        idx++;
    }

    // add null termination char if result is not null
    if (result) {
        result = (char*)realloc(result, ++result_size);
        result[result_size - 1] = '\0';
        free(*target);
    } else {
        result_size = 1; // fixes negative return thing. I'm so lazy
    }

    *target = result;

    return result_size - 1; // ignore null termination
}

bool is_palindrome(char *src, size_t size) {
    size_t i = 0;
    size_t j = size - 1;

    while(i < size) {
        if(src[i] != src[j])
            return false;
        i++;
        j--;
    }
}

int main()
{
    while(1) {
        char *input = NULL;
        size_t size = getl(&input);
        if(!input)
            // input is empty or EOF
            break;

        // remove all non alphabets
        size = filter_alphabets(&input, size);

        if(is_palindrome(input, size))
            printf("Palindrome\n");
        else
            printf("Not Palindrome\n");

        free(input);
    }
}