array as a stack, and pushes the passed
variables onto the end of
array increases by the number of
variables pushed. Has the same effect as:
Returns the new number of elements in the array.
Note: If you use array_push() to add one element to the array it's better to use $array = because in that way there is no overhead of calling a function.
Note: array_push() will raise a warning if the first argument is not an array. This differs from the $var behaviour where a new array is created.