SWI-Prolog -- number

Availability:built-in

[ISO]number_chars(?Number, ?CharList)

Similar to atom_chars/2, but converts between a number and its representation as a list of one-character atoms. Fails with a syntax_error if Number is unbound or CharList does not describe a number. Following the ISO standard, it allows for leading white space (including newlines) and does not allow for trailing white space.^{101ISO
also allows for Prolog comments in leading white space. We--and most
other implementations--believe this is incorrect. We also beleive it
would have been better not to allow for white space, or to allow for
both leading and trailing white space. Prolog syntax-based conversion
can be achieved using format/3
and read_from_chars/2.}