Name Arranger program- error C2228

[skididdy93]

I am building a name arranger that takes in a full name and sorts it in the order of lastname, firstname middlename. I get an error when trying to pull length of array. (Error C2228 left of '.length' must have class/struct/union)
I have read through the chapter again and still don't seem to understand what the issue is. Thank you for reading

  #include <iostream>
#include <cstring>
using namespace std;

int main()
{
	const int size =100;
	char firstname[size];
	char middlename[size];
	char lastname[size];
	int length = 0;
	

	cout << "Please enter your first name: ";
	cin.getline(firstname, size);
	length += firstname.length();

	cout << "Please enter your middle name: ";
	cin.getline(middlename, size);
	length += middlename.length();

	cout << "Please enter your last name: ";
	cin.getline(lastname, size);
	length += lastname.length();

	char fullname[length +1];

	fullname.copy(lastname);
	fullname.copy(firstname);
	fullname.copy(middlename);

	cout << fullname[length];


}

[MiiNiPaa]

firstname is array of characters. It cannot have members, like length(), and in fact arrays in C++ are dumb and do not know hteir size.

You probably meant for firstname to be as std::string.