Difference between procedural programming and object oriented programming

Traditional Procedural Programming

In traditional, procedural programming, data and functions (subroutines, procedures) are
kept separate from the data they process. This has a significant effect on the way a pro-
gram handles data:
■ the programmer must ensure that data are initialized with suitable values before
use and that suitable data are passed to a function when it is called
■ if the data representation is changed, e.g. if a record is extended, the correspon-
ding functions must also be modified.
Both of these points can lead to errors and neither support low program maintenance
requirements.

Objects-oriented programming 

Object-oriented programming shifts the focus of attention to the objects, that is, to the
aspects on which the problem is centered. A program designed to maintain bank
accounts would work with data such as balances, credit limits, transfers, interest calcula-
tions, and so on. An object representing an account in a program will have properties
and capacities that are important for account management.
OOP objects combine data (properties) and functions (capacities). A class defines a
certain object type by defining both the properties and the capacities of the objects of
that type. Objects communicate by sending each other “messages,” which in turn acti-
vate another object’s capacities.

Advantages of OOP

Object-oriented programming offers several major advantages to software development:
■ reduced susceptibility to errors: an object controls access to its own data. More
specifically, an object can reject erroneous access attempts
■ easy re-use: objects maintain themselves and can therefore be used as building
blocks for other programs
■ low maintenance requirement: an object type can modify its own internal data
representation without requiring changes to the application.                                                               

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