printf ( format-string -- quot ) (original) (raw)

Inputs

Outputs
None

Word description
Writes the arguments (specified on the stack) formatted according to the format string.

Several format specifications exist for handling arguments of different types, and specifying attributes for the result string, including such things as maximum width, padding, and decimals.

%%	Single %
%P.Ds	String	string
%P.DS	String uppercase	string
%P.Du	Unparsed	object
%c	Character	char
%C	Character uppercase	char
%LPd	Integer decimal (base 10)	real
%LPx	Integer hexadecimal (base 16)	real
%LPX	Integer hexadecimal uppercase (base 16)	real
%LPo	Integer octal (base 8)	real
%LPb	Integer binary (base 2)	real
%LP.De	Scientific (base 10)	real
%LP.DE	Scientific uppercase (base 10)	real
%LP.Df	Fixed (base 10)	real
%[%?, %]	Sequence	sequence
%[%?: %? %]	Assocs	assoc

Leading (L) is used to optionally prefix a plus sign ("+") or space (" ") if the formatted number is positive.

Padding (P) is used to optionally specify the minimum width of the result string, the padding character, and the alignment. By default, the padding character defaults to a space and the alignment defaults to right-aligned. For example:

•	%5s formats a string padding with spaces up to 5 characters wide.
•	%03d formats an integer padding with zeros up to 3 characters wide.
•	%'#10f formats a float padding with # up to 10 characters wide.
•	%-10d formats an integer to 10 characters wide and left-aligns.

Digits (D) is used to optionally specify the maximum digits in the result string. For example:

•	%.3s formats a string to truncate at 3 characters (from the left).
•	%.10f formats a float to pad-tail with zeros up to 10 digits beyond the decimal point.
•	%.5E formats a float into scientific notation with zeros up to 5 digits beyond the decimal point, but before the exponent.

Examples

USING: formatting ; 123 "%05d" printf
00123

USING: formatting ; 0xff "%04X" printf
00FF

USING: formatting ; 12 "%b" printf
1100

USING: formatting ; 1.23456789 "%.3f" printf
1.235

USING: formatting ; 12 "%'#4d" printf
##12

USING: formatting ; 1234 "%+d\n" printf -1234 "%+d\n" printf 1234 "% d\n" printf
+1234 -1234 1234

USING: formatting ; { 1 2 3 } "%[%d, %]" printf
{ 1, 2, 3 }

USING: formatting ; H{ { 1 2 } { 3 4 } } "%[%d: %d %]" printf
{ 1:2, 3:4 }

USING: calendar formatting ; 3 years "%u" printf
T{ duration { year 3 } }

Definition