Function Definitions

11 - Printing to Screen

Summary:

	Accepts both strings and numbers	Prints control characters	Prints new line and trailing space	Quotation marks for strings	Returns (when printing strings)
prin1	yes	verbatim	no	"xxxxxx"	"xxxxxx"
princ	yes	interpreted	no	xxxxxx	"xxxxxx"
print	yes	verbatim	yes	"xxxxxx"	"xxxxxx"
prompt	strings only	interpreted	no	xxxxxx	nil

prin1 ..... Prints an expression (string or numbers) on the screen or to a file and returns the expression

(prin1 'a) prints A and returns A
(prin1 "hello") prints "hello" and returns "hello"
After (setq a 15.9 b "good bye")
(prin1 a) prints 15.9 and returns 15.9
(prin1 b) prints "good bye" and returns "good bye"
(prin1 b fw) prints "good bye" to the file buffer identified by variable fw (assuming it has already been opened for writing) and returns "good bye"
(prin1 (chr 10)) prints "\n" verbatim and returns "\n"
(prin1) returns nothing. Can be used as the last function in a program to cancel the display of "nil" or other extraneous output.

princ ..... Similar to prin1 (see prin1 above) except control characters such as (chr 10) are interpreted when printed rather than printed verbatim

The following control characters will function as described when made part of a string (included in quotation marks):
\n carriage return and line feed (new line)
\r carriage return only (cursor stays on same line)
\t tab every 8 columns (9th, 17th, 25th, etc.)
\\ single backslash (useful for path names - or, a single forward slashes can be used in path names)
\e escape character (useful for sending escape codes to a printer, etc.)
\xxx character whose octal (base 8) code is xxx

print ..... Same as prin1 except the printed expression is preceded by a carriage return and line feed and followed by a space

prompt ..... Displays a string on the screen and returns nil, accepts only strings, and interprets control characters.

(prompt "Dog yummies") displays Dog yummies on the screen

terpri ..... Prints a new line on the screen

(terpri) prints carriage return and line feed, returns nil (not used for file output)

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