Node:Formatted output, Previous:Iterators, Up:Streams
To format data as a string, do:
sprintf format_string arg_1 ... arg_nThe args are formatted according to formatting directives in the string format_string.
To format data as a string, and send the result to the output text stream out_stream do:
out_stream printf format_string arg_1 ... arg_nIf out_stream is omitted, it defaults to the standard output file. Except for some pathological cases (and efficiency), this is the same as:
out_stream put (sprintf format_string arg_1 ... arg_n)@
An example:
:x=12 sprintf "[x=%05d]" 12 # Yields the string "[x=00012]"The text
"%05d" is a format directive which indicates
that the argument value (in this case 12) is to be written
using 5 decimal digits, filled with zeros on the left.
The rest of the format string ("[x=" and "]")
is emitted verbatim into the output.
A format control string is written in a form (syntax) similar to
the printf control strings in the C language.
However, the semantics is closer to the format control
strings in Common Lisp: formatting is is quite powerful,
and can take arguments that are typed.