error

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include<conio.h>

//void binary_hex(int n, char hex[]);
long long int hex_binary(char hex[]);

int main()
{
	char hex[20] = {'A','A','A'};
		char c=0;
	int n = 0;	
	printf("Binary number: %lld", hex_binary(hex));

	getch();
	return 0;
}

//Function to convert hexadecimal to binary.

long long int hex_binary(char hex[]) {

	int i, length, decimal = 0;
	long long int binary = 0;
	for (length = 0; hex[length] != '\0'; ++length);

	for (i = 0; hex[i] != '\0'; ++i, --length)
	{
		if (hex[i] >= '0' && hex[i] <= '9')
			decimal += (hex[i] - '0')*pow(16, length - 1);
		if (hex[i] >= 'A' && hex[i] <= 'F')
			decimal += (hex[i] - 55)*pow(16, length - 1);
		if (hex[i] >= 'a' && hex[i] <= 'f')
			decimal += (hex[i] - 87)*pow(16, length - 1);
	}
	//At this point, variable decimal contains the hexadecimal number in decimal format. 

	i = 1;
	while (decimal != 0)
	{
		binary += (decimal % 2)*i;
		decimal /= 2;
		i *= 10;
	}

	return binary;
}

fix by win htut

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include<conio.h>
#define WinHtut 100


 int hex_binary(char hex[]);
 int result[WinHtut];
  int x = 0;
  int y = 0;

int main()
{
	char hex[20] = {'A','A','A'};
	
	int i, length, decimal = 0;

	for (length = 0; hex[length] != '\0'; ++length);

	for (i = 0; hex[i] != '\0'; ++i, --length)
	{
		if (hex[i] >= '0' && hex[i] <= '9')
			decimal += (hex[i] - '0')*pow(16, length - 1);
		if (hex[i] >= 'A' && hex[i] <= 'F')
			decimal += (hex[i] - 55)*pow(16, length - 1);
		if (hex[i] >= 'a' && hex[i] <= 'f')
			decimal += (hex[i] - 87)*pow(16, length - 1);
	}
	printf("%d\n", decimal);
	while (decimal != 0)
	{
		result[x] =decimal % 2;
		decimal = decimal / 2;
			
		x++;
	}
	printf("The number of Stored in the Array is %d\n", x);
	printf("The binary value of the A A A is = ");
	for (y = x - 1; y >= 0; y--) {
		printf("%d", result[y]);	
	
	}

	getch();
	return 0;
}