List of top Computer Science Questions on file handling asked in CPET

What will the following C++ program do?

#include <iostream>
#include <fstream>
using namespace std;
int main() {
 ofstream file("example.txt", ios::app);
  file << "Hello ";
  file.close();
  return 0;
}

What will happen if you do not call fclose(fp), after opening a file in C?