Hello World

The header file std_lib_facilities.h is provided to simplify the use of standard library facilities. It is used with #include directive to make them available in the code.

// This program outputs the message "Hello, World!"

#include "../std_lib_facilities.h"

int main() // C++ programs start by executing the function main
{
    cout << "Hello, World!\n";
    return 0;
}

In C++, string literals are delimited by double quotes (") from both sides. The \n is a special character indicating a new line. The name cout refers to a standard output stream. Characters are forwarded to cout stream using the output operator <<. A comment line starts with the token //.

Every C++ program must have a function called main to tell it where to start executing the code. A function has the following parts: - A return type, here int. - A name, here main. - A parameter list enclosed in parentheses, here (). - A function body enclosed in curly braces {} lists the actions for the function to execute. Such actions are called statements.

In the above program, the main() function returns the value 0 to whoever called it. Since main() is called by the system, we don't use this return value. However, in Unix, a zero value returned by main() indicates that the program terminates successfully.

C++ is a compiled language. It first translates human-readable code to machine instructions called object code by a program called a compiler. Then a program called a linker combines machine instructions from separate parts (for example, the code we have written and the parts from C++ standard library) into an executable program. The executable programs cannot be used across different operating systems.

There are compile-time errors found by the compiler, link-time errors found by the linker, and run-time errors found when the program is run. Debugging is the activity of finding errors in a program and removing them.