printf ( format-string -- quot )
Formatted printing

Next:sprintf ( format-string -- quot )


format-stringa string


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.DSString uppercasestring
%CCharacter uppercasechar
%LPdInteger decimal (base 10)real
%LPxInteger hexadecimal (base 16)real
%LPXInteger hexadecimal uppercase (base 16)real
%LPoInteger octal (base 8)real
%LPbInteger binary (base 2)real
%LP.DeScientific (base 10)real
%LP.DEScientific uppercase (base 10)real
%LP.DfFixed (base 10)real
%[%?, %]Sequencesequence
%[%?: %? %]Assocsassoc

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.

USING: formatting ; 123 "%05d" printf

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

USING: formatting ; 12 "%b" printf

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

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

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 } }