retrieve the character code of the character at the current stream position.
peek_code/1 retrieves the character code of the character at the stream position of the current input stream.
peek_char/2 retrieves the character code of the character at the stream position of the stream Stream.
The stream position will not be altered by these predicates.
peek_code retrieves the character code of the character at the current stream position and unifies it with Code. If the stream position is behind the end of the inputstream, Code will be unified with -1.
Stream text input stream Code integer (unicode or -1)
Assume the content of a stream S is abcdefg and the stream position is at the 1st character.
| peek_code(0'a). | Succeeds. The stream position will not be altered. |
| peek_char(C). | Succeeds with substitution(C<-0'a). The stream position will not be altered. |
These predicates are part of the ISO-Prolog Standard.
get_char/1/2, get_code/1/2, peek_char/1/2, put_char/1/2, put_code/1/2, nl/0/1, set_input/1, current_input/1.