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read_string(+Delimiters, ?Length, -String)

Reads a string from the input stream up to a delimiter or up to a specified length
String or atom.
Integer or variable.
String or variable.


A string of characters is read from the input up to one character which occurs in the delimiter string Delimiters. This character is also consumed, but does not appear in the string which is unified with String. Two symbolic Delimiters can be specified:

    end_of_line   a newline or carriage-return/newline sequence
    end_of_file   the end of the file/input
End of file always acts like a delimiter.

If Length is a variable, it is unified with the length of the string String. If Length is an integer, the number of characters read from the input is limited by the Length.

Modes and Determinism

Fail Conditions

There is nothing to read, i.e. the stream is at end_of_file


(4) instantiation fault
Delimiters is not instantiated.
(5) type error
Delimiters is not a string or atom.
(5) type error
Length is not an atom or an integer.
(5) type error
String is not an atom or a string.
(6) out of range
Delimiters is an atom but not a valid symbolic delimiter.
(190) end of file reached
End of file was encountered before reading any character.
(198) reading past the file end
Trying to read even after the error 190 was raised.


   Equivalent to read_string(input, Delimiters, Length, String).  (see
   read_string/4 for details).

See Also

read_string / 4, read_token / 2, read_token / 3, open / 3