Need to create two functions to write structure dynamic array with strings into bin file and another funtion to read

Hi

I have structure dynamic array, which contains several variables including string type.

So I need to make two functions to write the whole array into bin file and read, I mean to recover the array from the file.

Both functions need to have option to merge or replace existing values in both directions, for example when writing into bin file it can erase everything and write the whole array de novo, or it can merge the array and existing data in the bin file. The same when reading. 

It is preferred to not use standard library classes.