array_shift shifts the first value of the
array off and returns it, shortening the
array by one element and moving everything
down. All numerical array keys will be modified to start counting from zero
while literal keys won't be touched.
Note: This function will
reset the array pointer of the input array after
use.
Parameters
array
The input array.
Return Values
Returns the shifted value, or NULL if array is
empty or is not an array.