What does this program do?

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

int main(){
ifstream file1(“text1.txt”, ios::binary);
ofstream file2(“text2.txt”, ios::binary);
file2 << file1.rdbuf();
}

• It renames text1.txt to text2.txt.
• It makes a directory called text2.txt and moves text1.txt there.
• It copies the contents of text1.txt into text2.txt – i.e., it makes a copy of text1.txt, named text2.txt.
• It appends the contents of text1.txt into text2.txt – i.e., replaces the contents of text2.txt by the concatenation of text2.txt and text1.txt.