main routine by the system. In the Hello World! program, we have only two such statements.
The first statement tells that a routine named printf is to be invoked or called. The string of characters “hello world! \n” is the parameter or argument to be passed to the printf routine. Just remember that the printf routine is a function in the C library. It simply prints or displays its
arguments on your screen in between double quotation marks. Also note that a blank space in a string
counts as a character.
Also seen in line 4 are two special characters—the backslash (\) and the letter n—that are together
known as the