Array#shift

() -> Elem

(::int n) -> ::Array[Elem]

shift → object or nil

shift(count) → new_array or nil

static VALUE
rb_ary_shift_m(int argc, VALUE *argv, VALUE ary)
{
    VALUE result;
    long n;

    if (argc == 0) {
        return rb_ary_shift(ary);
    }

    rb_ary_modify_check(ary);
    result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
    n = RARRAY_LEN(result);
    rb_ary_behead(ary,n);

    return result;
}

Removes and returns leading elements from self.

With no argument, removes and returns one element, if available, or nil otherwise:

Example

a = [0, 1, 2, 3]
a.shift  # => 0
a        # => [1, 2, 3]
[].shift # => nil

With non-negative numeric argument count given, removes and returns the first count elements:

Example

a = [0, 1, 2, 3]
a.shift(2)   # => [0, 1]
a            # => [2, 3]
a.shift(1.1) # => [2]
a            # => [3]
a.shift(0)   # => []
a            # => [3]

If count is large, removes and returns all elements:

Example

a = [0, 1, 2, 3]
a.shift(50) # => [0, 1, 2, 3]
a           # => []

If self is empty, returns a new empty array.

Related: see Methods for Deleting.

See also #shelljoin #shuffle #select! #shuffle! also in 4.1 · 4.0 · 3.3 · 3.2 · 3.1 · 3.0

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