SWI-Prolog -- format/3

Documentation
- Reference manual
  - Built-in Predicates
    - Formatted Write
      - Format
        
        format/1
        
        format/2
        
        format/3
- Packages

Availability:built-in

format(+Output, +Format, :Arguments)

As format/2, but write the output on the given Output. The de-facto standard only allows Output to be a stream. The SWI-Prolog implementation allows all valid arguments for with_output_to/2.^{148Earlier
versions defined sformat/3 . These predicates have been moved to the
library library(backcomp).} For example:

?- format(atom(A), '~D', [1000000]).
A = '1,000,000'

Examples

Convert an integer to a string of 0s and 1s

Take advantage of format/3 to convert an integer to a string of 0s and 1s with a given minimum length, padding with 0s on the left if necessary.

int_to_binary_str(Int, Length, Str) :-
    format(string(Str), '~`0t~2r~*|', [Int, Length]).

?- int_to_binary_str(10, 1, Str).
Str = "1010".

?- int_to_binary_str(10, 10, Str).
Str = "0000001010".