The substr () function is used to return the part of a string located between a predefined starting offset and length position.

The explode () function is used divides the string into an array of substrings.

To remedy the problems with copying, PHP offers an explicit means for cloning an object is known as object cloning. We can clone an object by preprefacing with the clone keyword.

The array_merge() function merges one ore more arrays into one array. This function returns one array with the elements of all the parameter arrays.

Syntax is array_merge(array1,array2,array3...)
The array_slice () function returns a section of an array based on a starting and ending offset value.
Syntax is array_slice(array,start,length,preserve)

There are four functions used to add to and remove from array elements. these are-

1. array_unshift():function adds element to the front of the array.
2. array_push(): function adds element to the end of an array.
3. array_shift(): function removes and returns the first item found in an array.
4. array_pop():function removes and returns the last element from an array.