term_variables_count(?Term, -N)

Term

Prolog term.

N

Variable or integer.

Description

This predicate counts the number of different variables in Term. Repeat occurrences of variables are ignored.

As usual, attributed variables are also considered variables.

This predicate can handle cyclic terms.

Modes and Determinism

• term_variables_count(?, -) is det

Examples

    term_variables_count(f(bar), N)       gives N=0
    term_variables_count(f(X,b,Y), N)     gives N=2
    term_variables_count(f(X,Y,X), N)     gives N=2
    term_variables_count(X, N)            gives N=1
    X=f(X), term_variables_count(X, N)    gives N=0
    X=f(X,Y), term_variables_count(X, N)  gives N=1

See Also