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writef.pl -- Old-style formatted write
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This library provides writef/1 and friends. These predicates originate from Edinburgh C-Prolog and and provided for compatibility purposes. New code should use format/1, format/2 and friends, which are currently supported by more Prolog implementations.

The writef-family of predicates conflicts with the modern character-esacapes flag about the interpretation of \-sequences. This can be avoided by

  1. Disable character escapes (not recommended unless one wants to run really outdated code unmodified).
  2. Double the \ for conflicting interpretations
  3. Use ISO compliant alternatives for conflicting interpretations
Source writef(+Format) is det
Source writef(+Format, +Arguments) is det
Formatted write to the current_output. Format is a format specifier. Some escape sequences require arguments that must be provided in the list Arguments. There are two types of escape sequences: special characters start with \ and include arguments start with %. The special character sequences are:
\nOutput a newline character
\lOutput a line separator (same as \n)
\rOutput a carriage-return character (ASCII 13)
\rOutput a TAB character (ASCII 9)
\\Output \
\%Output %
\nnnOutput character <nnn>. <nnn> is a 1-3 decimal number

Escape sequences to include arguments from Arguments. Each time a %-escape sequence is found in Format the next argument from Arguments is formatted according to the specification.

%tprint/1 the next item (mnemonic: term)
%wwrite/1 the next item
%qwriteq/1 the next item
%ddisplay/1 the next item
%nPut the next item as a character
%rWrite the next item N times where N is the second item (an integer)
%sWrite the next item as a String (so it must be a list of characters)
%fPerform a ttyflush/0 (no items used)
%NcWrite the next item Centered in N columns.
%NlWrite the next item Left justified in N columns.
%NrWrite the next item Right justified in N columns.
- New code should use format/1, format/2, etc.
Source swritef(-String, +Format) is det
Source swritef(-String, +Format, +Arguments) is det
Use writef/1 or writef/2 and write the result to a string. Note that this is a string in the sense of string_codes/2, not a list of character(-code)s.
- . See format/2,3 and/or with_output_to/2.

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

Source swritef(Arg1, Arg2, Arg3)
Source writef(Arg1, Arg2)