Yury Luneff wote :
You see, I've got something like this:
| ?- read(Hello).
Hello.
yes
| ?- write(Hello).
_16
This is not what I've expected to see and because of this my program
doesn't work as it should. What do I have to do with this or
everything's normal?
You have to look at the syntax of Prolog terms. I suppose you want to
read/write the constant "Hello". In Prolog a constant must be quoted
like this 'Hello'. However, for a easier use, a constant which begins
with a lower case letter (a-z) and followed by letters, digits or _ does
not need quotes. So 'hello' can be simply written as hello (without
quotes) but 'Hello' cannot be written without quotes. Indeed, if the
first character is an upper case letter (A-Z) then it is considered as
the name of a variable (not a constant). So use :
| ?- read(X).
'Hello'.
X = 'Hello'
yes
| ?- write('Hello').
Hello
yes
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