[ Event Handling | Reference Manual | Alphabetic Index ]

current_error(?N)

Succeeds if N unifies with a valid error number.
N
Positive integer or variable.

Description

Used to generate on backtracking all the current valid error numbers. N is a variable.

Also used to check that N is a valid error number. N is an integer.

Modes and Determinism

Fail Conditions

Fails if N is not a valid error number.

Exceptions

(5) type error
N is instantiated, but not to an integer.

Examples

Success:
      ?- current_error(N).
      N = 1     More? (;)       % type `;'
      N = 2     More? (;)
      N = 4     More? (;)
      N = 5     More? (;)       % carriage return typed
      yes.

      ?- [user].
       list_error1(String, N, Message) :-
              current_error(N),
              error_id(N, Message),
              substring(Message, String, _).
       user compiled 208 bytes in 0.03 seconds

      ?- list_error1("def",N,M).
      N = 21
      M = "undefined arithmetic expression"     More? (;)
      yes.

Fail:
      current_error(3).

Error:
      current_error(1.0).   (Error 5).

See Also

error_id / 2