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/*

 *  call-seq:

 *     ary.has_index?(idx)    -> true or false

 *     ary.index?(idx)        -> true or false

 *

 *  Returns <code>true</code> if the given index is present in <i>ary</i>.

 *

 *     a = [ "a", "b", "c" ]

 *     h.has_index?(0)    #=> true

 *     h.has_index?(2)    #=> true

 *     h.has_index?(3)    #=> false

 *     h.has_index?(-1)   #=> true

 *     h.has_index?(-4)   #=> false

 *

 */

static VALUE

rb_ary_has_index(VALUE ary, VALUE pos)

{

    VALUE val;

    long idx;

    idx = NUM2LONG(pos);

    if (idx < 0) {

       idx += RARRAY_LEN(ary);

    }

    if (idx < 0 || RARRAY_LEN(ary) <= idx) {

       return Qfalse;

    }

    return Qtrue;

}

    rb_define_method(rb_cArray, "has_index?", rb_ary_has_index, 1);

    rb_define_method(rb_cArray, "index?", rb_ary_has_index, 1);

  def test_has_index

    a = @cls[ 'cat', 99, /a/, 99, @cls[ 1, 2, 3] ]

    assert(  a.has_index?(0))

    assert(  a.has_index?(4))

    assert(! a.has_index?(5))

    assert(  a.has_index?(-1))

    assert(  a.has_index?(-5))

    assert(! a.has_index?(-6))

  end