11.3.218 sub_atom/5 [ISO]

Synopsis

sub_atom(+Atom,-Before,-Length,-After,-SubAtom)

The characters of SubAtom form a sublist of the characters of Atom, such that the number of characters preceding SubAtom is Before, the number of characters after SubAtom is After, and the length of SubAtom is Length.

Arguments

Atom

atom, must be nonvar

The atom from which a part is selected.

Before

integer

The number of characters preceding SubAtom.

Length

integer

The number of characters of SubAtom.

After

integer

The number of characters following SubAtom.

SubAtom

atom

The selected part of Atom.

Description

Capable of nondeterminately enumerating all sub-atoms and their all possible placements, e.g.:

     | ?- sub_atom(abrakadabra, Before, _, After, ab).
     
     After = 9,
     Before = 0 ? ;
     
     After = 2,
     Before = 7 ? ;
     
     no

Exceptions

instantiation_error

Atom is uninstantiated.

type_error

Atom is not an atom. Before, Length, or After, if instantiated, is not an integer. SubAtom, if instantiated, is not an atom.

domain_error

Before, Length, or After, if instantiated, is negative.

See Also

atom_length/2, atom_concat/3.