PROGRAMMING LANGUAGES The Study of Programming Languages

OBJECTIVES At the end of the lesson, the student must be able to: 1.Define what is programming language 2.Identify the reasons of studying programming language 3.Identify the history of programming languages 4.Determine the criteria for a good p.l.

PROGRAMMING LANGUAGE Any notation for the description of algorithms and data structures Requires that programming language is implemented on computers A programming language is an artificial language designed to express computations that can be performed by a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine, to express algorithms precisely, or as a mode of human communication. (Wikipedialanguagecomputationsmachinecomputerprograms algorithms EX. PASCAL, C, JAVA, C++, VISUAL BASIC, ADA, LISP, FORTRAN, COBOL, PROLOGUE

WHY STUDY PROGRAMMING LANGUAGES? 1.To improve your understanding of the language you are using. – Many languages provide features when used properly are of benefit to the programmer but when used improperly may waste large amounts of computer time or lead the programmer into time-consuming logical errors. Ex. Use of array and single variable data storage

WHY STUDY PROGRAMMING LANGUAGES? 2. To increase your vocabulary of useful programming constructs. – Language or the syntaxes/commands aid the programmer to implement the logic of the program – In searching for the data and program structures suitable to the solution of a problem, one tends to think only of structures that are immediately expressible in the languages with which one is familiar. – By studying the constructs provided by the wide range of languages and the manner in which these constructs are implemented, the programmer increases his programming “vocabulary”.

WHY STUDY PROGRAMMING LANGUAGES? 3. To allow better choice of programming language Ex. C and Java 4.To make it easier to learn a new language -A thorough knowledge of a variety of programming language constructs and implementation techniques allows the programmer to learn constructs and implementation techniques allows the programmer to learn a new language more easily when the need arises

WHY STUDY PROGRAMMING LANGUAGES? 5.To make it easier to design a new language – The user interface can be designed by a programmer if he has a thorough knowledge of the p.l. – The user interface consists of the commands and data formats that are provided for the user to communicate with the program – The aspect of program design is often simplified if the programmer is familiar with a variety of constructs and implementation methods from ordinary programming languages.

INFLUENCES ON THE EVOLUTION OF LANGUAGE DESIGNS 1.COMPUTER HARDWARE AND OPERATING SYSTEM – Evolved from small, slow, and costly vacuum- tube machines to microcomputers. – At the same time, layers of microprogram and operating system software have been inserted between the programming language and the underlying computer hardware. This factors have influenced both the structure and the cost of using the features of high-level languages.

INFLUENCES ON THE EVOLUTION OF LANGUAGE DESIGNS 2. Applications -from the original concentration on critical, military, scientific, business, and industrial applications in the 1950’s to educational, entertainment and other applications in the area of human activities seen today. - The requirements of these new application areas affect the designs of new languages and the revisions and extensions of older ones.

INFLUENCES ON THE EVOLUTION OF LANGUAGE DESIGNS 3.PROGRAMMING METHODS – Language designs have evolved to reflect our changing understanding of good methods for writing large and complex programs and to reflect the changing environment in which programming is done.

INFLUENCES ON THE EVOLUTION OF LANGUAGE DESIGNS 5.THEORETICAL STUDIES – Research into the conceptual foundations for language designs and implementations, using formal mathematical methods, has deepened our understanding of the strengths and weaknesses of language features and has thus influenced the inclusion of these features in new language designs

INFLUENCES ON THE EVOLUTION OF LANGUAGE DESIGNS 6.Standardization. - the need for “standard” language that can be implemented easily on a variety of computer systems and that allow programs to be transported from one computer to another has provided strong conservative influence on the evolution of language history

WHAT MAKES A GOOD LANGUAGE? 1.Clarity, simplicity, and unity of language concept – PL’s provides both the conceptual framework for thinking about algorithms and a means of expressing those algorithms for machine execution – The language should be an aid to the programmer before he reaches the actual coding stage in programming. – It should provide him with clear, simple, and unified set of concepts that he can use as primitives in developing algorithms – It is desirable to have a minimum number of different concepts, with the rules for their combination being as simple and regular as possible

WHAT MAKES A GOOD LANGUAGE? 2. Clarity of program syntax. – Syntax greatly affects the ease with which the program may be written, tested, and later understood and modified. – Some syntaxes are easy to write but difficult to be modified – It is important that a syntax is not misleading or must be error-prone to reflect the underlying logical structure of the algorith – Structured and object oriented programming languages are easy to implement and understand compared to the first generation languages

WHAT MAKES A GOOD LANGUAGE? 3. NATURALNESS OF APPLICATIONS. -The language should provide appropriate data structures, operations, control structures, and a natural proliferation of languages is just this need for naturalness

WHAT MAKES A GOOD LANGUAGE? 4.SUPPORT FOR ABSTRACTION – There is always a gap remaining between the abstract data structures and operations that characterize the solution to a problem and the particular primitive data structures and operations built into a language. – The language should allow data structures, data types, and operations to be defined and maintained as self-contained abstraction, so the programmer may use them in other parts of the program knowing only their abstract properties, without concern for the details of their implementations.

What Makes a GOOD LANGUAGE? 5.PROGRAMMING ENVIRONMENT – The technical structure of the programming language is only one aspect affecting its utility – The presence of a programming environment may make a programming language easier to work than a stronger language that has little external support Ex. compilers, text editors and other utilities for the pl’s must be available. -other pl’s are licensed while others are for free

WHAT MAKES A GOOD LANGUAGE? 6. PORTABILITY OF THE PL. 7.COST OF USE 1.COST OF PROGRAM EXECUTION 2.COST OF PROGRAM TRANSLATION 3.COST OF PROGRAM CREATION,TESTING, AND USE 4.COST OF PROGRAM MAINTENANCE

Read/study PL PROCESSORS – STRUCTURE AND OPERATIONS OF A COMPUTER – TRANSLATORS AND SOFTWARE SIMULATED COMPUTERS – SEMANTICS AND SYNTAX AND ITS IMPLEMENTATIONS