array_change_key_case () is an another PHP prebuilt / default array function, This function is basically allows user to do the array keys lower or uppercase. It will rturn null and will Throw E_WARNING if array is not an array.
array_pop () is a prebuilt / default array function of PHP, This function is basically allows user to delete the last element of any existing array. By using this function user can short the array by one element
array_push () is a prebuilt / default array function of PHP, This function is basically allows user to add one or more elements at the end of any existing array. By using this function user can add any number of the element at the end, and this element can
PHP has very strong array features by using the array, it is very easy to use and access the data in PHP, By default PHP provides many array functions to access and manipulate the elements of array.