#### 15.2.31 vector-push, vector-push-extend [Function]

`vector-push` new-element vector ⇒ new-index-p

`vector-push-extend` new-element vector &optional extension ⇒ new-index

#### Arguments and Values::

new-element—an object.

vector—a vector with a fill pointer.

extension—a positive integer. The default is implementation-dependent.

new-index-p—a valid array index for vector, or nil.

new-index—a valid array index for vector.

#### Description::

vector-push and vector-push-extend store new-element in vector. vector-push attempts to store new-element in the element of vector designated by the fill pointer, and to increase the fill pointer by one. If the `(>= (fill-pointer vector) (array-dimension vector 0))`, neither vector nor its fill pointer are affected. Otherwise, the store and increment take place and vector-push returns the former value of the fill pointer which is one less than the one it leaves in vector.

vector-push-extend is just like vector-push except that if the fill pointer gets too large, vector is extended using adjust-array so that it can contain more elements. Extension is the minimum number of elements to be added to vector if it must be extended.

vector-push and vector-push-extend return the index of new-element in vector. If `(>= (fill-pointer vector) (array-dimension vector 0))`, vector-push returns nil.

#### Examples::

     (vector-push (setq fable (list 'fable))
                  (setq fa (make-array 8
                                       :fill-pointer 2
                                       :initial-element 'first-one))) ⇒  2
     (fill-pointer fa) ⇒  3
     (eq (aref fa 2) fable) ⇒  true
     (vector-push-extend #\X
                        (setq aa
                              (make-array 5
                                          :element-type 'character
                                          :adjustable t
                                          :fill-pointer 3))) ⇒  3
     (fill-pointer aa) ⇒  4
     (vector-push-extend #\Y aa 4) ⇒  4
     (array-total-size aa) ⇒  at least 5
     (vector-push-extend #\Z aa 4) ⇒  5
     (array-total-size aa) ⇒  9 ;(or more)

#### Affected By::

The value of the fill pointer.

How vector was created.

#### Exceptional Situations::

An error of type error is signaled by vector-push-extend if it tries to extend vector and vector is not actually adjustable.

An error of type error is signaled if vector does not have a fill pointer.

#### See Also::

adjustable-array-p , fill-pointer , vector-pop