print revisited

In chapter 1, we used the print phrase to convert internal values to external characters. We ought to say what print is and how it works, but we don't yet know enough about the language. Just use it for the moment, and we shall learn more about it later.

Besides being able to convert internal values to external characters, print can take two parameters (see chapter 6 for the low-down on parameters) which can be used to format your output. newline will cause following output to be displayed on a new line, and newpage will emit a form-feed character (REPR 12). newline and newpage will be described in detail in section 13.7.11.

If you want to print the characters emitted by your Algol 68 programs you can use file redirection to redirect your output to a file, which you can later copy to the printer. For example, suppose you have compiled a program called tt. To redirect its output to a file called tt.res, which you can later copy to the printer, you issue the command

   tt > tt.res

at the command line. Alternatively, you send the output directly to the printer using the command

   tt | lpr

at the command line. Try compiling and running the following program:

   PROGRAM tt CONTEXT VOID
   USE standard
   BEGIN
      print(newpage);
      INT a = ENTIER (3.6**5);
      REAL p = 4.3 / 2.7;
      print(a);  print(newline);
      print(b);  print(newline)
   END
   FINISH
Sian Mountbatten 2012-01-19