3. First C++ program, cont.

• 
      #include <iostream>
      int main()
      {
          std::cout << "Hello, World!";
          return 0;
      }
  
  

• Second line contains main entry point into our program.

• That is, when the program is loaded into memory, its execution begins here.

• The word "main" is the name of a C++ function. C++ functions define computer operations. Entire combination int main() suggests two things:

  1. main is a function with no input parameters, because parentheses are empty.

  2. keyword int declares that main function returns an integer (number) back to the operating system.

  Note: int and return are keywords (reserved words) of the C++ programming language.