PHP does not support multiple inheritances. PHP generally supports single type of inheritance.

Ans: Constant is a value that cannot be modified throughout the execution of a program.Constant are declared by using define () function.

Ans: The difference of print and printf are as the print statement is used output data passed to it, but the printf statement is used t output a blend of statement and dynamic information stored within one or several variable.

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

The array_slice() function returns selected parts of an array. The array_slice() function returns part of an array as specified by the start and length parameters. If start is a positive number, it means that the ”slice” will start that many elements from the beginning of the array.

Abstract class: An Abstract. Class is a class that cannot be instantiated but instead serves as a base class to be inherited by other classes.
Interface: An Interfaces is a collection of unimplemented method definitions and constantswithout specifying exactly how it must be implemented.