Array Functions

There are four functions for adding elements to and removing elements from arrays:

array_shift()	removes an item from the beginning of an array
array_unshift()	adds an item to the beginning of an array
array_pop()	removes an item from the end of an array
array_push()	adds an item to the end of an array

Other useful array functions:

max() & min()	Return the largest and smallest numerical values in the array.
array_sum()	Adds all the numerical values in an array and returns the sum. Non-numerical values are ignored.
sort()	Reorders the values in an array into alphabetical (actually "ASCIIbetical" order) or numerical order.
count()	Returns the number or elements in an array.
key_exists()	Particularly useful with associative arrays, this returns true if the value provided is a key in the array.