C :: Use Main Function To Ask For Input To Convert Hexadecimal To Binary

Code:

#include<stdio.h>#define MAX 1000
int main(){
char binaryNumber[MAX],hexaDecimal[MAX];
long int i=0;
printf("Enter any hexadecimal number: ");
scanf("%s",hexaDecimal);

[Code]...

So this is my current code, is there anyway I can reduce the size and use a main function to ask for input and a call function to do all the conversion and return it? I am confused for the past few days trying to figure it out and finally ended up here. Anyway can I write it as a something like this

Code:

int main()
{
//ask for user input hexadecimal into here and call a let's say hex2binary() function
}

int hex2binary(...)
{
//an array with dynamic memory, malloc? and convert it and return values
}

I don't really need the full code, just a simple instruction on how and where to start.