computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...

and

computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...

, access level denotes the set of permissions or restrictions provided to a data type. Reducing access level is an effective method for limiting failure modes, reducing debugging time, and simplifying overall system complexity. It restricts variable modification to only the methods defined within the interface to the class. Thus, it is incorporated into many fundamental

software design pattern In software engineering, a software design pattern is a general, reusable solution to a commonly occurring problem within a given context in software design. It is not a finished design that can be transformed directly into source or machine co ...

s. In general, a given object cannot be created, read, updated or deleted by any function without having a sufficient access level. The two most common access levels are ''public'' and ''private'', which denote, respectively; permission across the entire program scope, or permission only within the corresponding class. A third, ''protected'', extends permissions to all subclasses of the corresponding class. Access levels modifiers are commonly used in Java as well as C#, which further provides the ''internal'' level. In C++, the only difference between a

struct In computer science, a record (also called a structure, struct, or compound data) is a basic data structure. Records in a database or spreadsheet are usually called "rows". A record is a collection of '' fields'', possibly of different data typ ...

and a

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

is the default access level, which is ''private'' for classes and ''public'' for structs. To illustrate the benefit: consider a public variable which can be accessed from any part of a program. If an error occurs, the culprit could be within any portion of the program, including various sub-dependencies. In a large code base, this leads to thousands of potential sources. Alternatively, consider a private variable. Due to access restrictions, all modifications to its value must occur via functions defined within the class. Therefore, the error is structurally contained within the class. There is often only a single source file for each class, which means debugging only requires evaluation of a single file. With sufficient modularity and minimal access level, large code bases can avoid many challenges associated with complexity.

Example: Bank Balance Class

Retrieved from Java Coffee Break Q&A public class bank_balance Here, the imperative variable ''balance'' is defined as a ''private int''. This ensures other classes, methods and functions cannot accidentally overwrite the variable balance. Instead, they must access the interface for the class ''bank_balance'', whose methods ensure the balance cannot drop below 0.

References

{{Reflist Computer security