Euler Project 4: Finding the largest palindrome product - arrays

Question

So, I've wrote several function prototypes for finding the largest palindrome products. The idea is that put the original number into an array in reverse order then convert the array into a number as reverse number. Then compare the reverse number with original number to see if these two numbers are equal or not. However, I am stuck at implementing these functions prototypes in main method. If yes, then it is a palindrome product/ Any suggestions? Please, have mercy I am new to C
#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
// Taking a number and reverse it. Put it in reverse order into an array. Then, convert all elements in the array into an array again
//Ex: Original number = 6542
//Input: "6542" -> arr[4] = {2,4,5,6} -> Output: "2456"
//Original Number = 6542; Reverse Number = 2456
//Original Number != Reverse Number -> The number is not palindrome. Palindrome Number Example: 456654, 1, 2332.
int convert_reverse_num (int original_num, int digits_count){
int arr_size = digits_count;
int x = original_num;
int final_reverse_num = 0;
int *arr;
arr = (int*)malloc (arr_size * sizeof(int));
//convert the number into arr array by placing the first index with the last trailing digit on the right
for (int i = 0; i < arr_size; i++){
arr[i] = x % 10;
x /= 10;
}
//Adding all values in the array into a number
//starting from the first index of the array which has the value of the last digit of the number
for (int i = 0; i < arr_size; i++){
final_reverse_num *= 10;
final_reverse_num += arr[i];
}
free(arr);
return final_reverse_num;
}
//Check the number is palindrome or not by comparing the original num and reverse num
bool is_palindrome(int original_num, int reverse_num){
int x = original_num;
int y = reverse_num;
if(x == y)
return 1;
else
return 0;
}
//Count number of digits in a number in order to declare the buffer size
int count_digit_num(int product_digits){
int y = product_digits;
int digits_count = 0;
while(y!=0){
y /= 10;
++digits_count;
}return digits_count;
}
//Find all possible products from two ndigits(2 digits, 3 digits, 4 digits) number
// Examples: 1 digits: 1*2. 2 digits: 12*13. 3 digits: 100 * 999
int find_largest_palindrome(int ndigits){
int min = 1;
int max;
int smallest_num;
int largest_num = 0;
int product = 0;
//Finding the minima. 1 digit = 1; 2 digits = 10; 3 digits = 100
smallest_num = min * pow(10, ndigits-1);
//Finding the maxima. 1 digits = 9; 2 digits = 99; 3 digits = 999
for (int i = 0; i < ndigits; i++){
max = 9 * pow(10, i);
largest_num += max;
}
//All possible products from minima and maxima
for (int x = largest_num; x >= smallest_num; x--){
for (int y = largest_num; y >= smallest_num; y--){
product = x * y;
}
}
return product;
}
int main(){
return 0;
}