C++ program to display "Hello World"

    #include <iostream>
    using namespace std;

    int main() { // Main() function: where the execution of program begins
      cout<<"Hello World"; // prints hello world
      return 0;
    }
        

• #include:
  • all lines that start with pound (#) sign are called directives and are processed by a preprocessor which is a program invoked by the compiler.
  • The #include directive tells the compiler to include a file.
  • #include<iostream>. It tells the compiler to include the standard iostream file which contains declarations of all the standard input/output library functions.
• using namespace std:
  • used to import the entirety of the std namespace into the current namespace of the program.
  • The std namespace is huge. So the statement using namespace std is generally considered a bad practice.
  • The alternative to this statement is to specify the namespace to which the identifier belongs using the scope operator(::) each time we declare a type.
• int main()
  • used to declare a function named "main" which returns data of integer type.
  • Execution of every C++ program begins with the main() function, no matter where the function is located in the program.
• std::cout<<"Hello World";
  • tells the compiler to display the message "Hello World" on the screen.
  • A semi-colon ; is used to end a statement. Semi-colon character at the end of the statement is used to indicate that the statement is ending there.
  • The std::cout is used to identify the standard character output device which is usually the desktop screen. Everything followed by the character << is displayed to the output device.
• return 0;
  • This statement is used to return a value from a function and indicates the finishing of a function.

    // this is a single line comment
    /*
      this is a
      multi-line comment
    */