csc chp 1

1. Introduction to Programming Languages

1.1 Reasons for Studying Concepts of Programming Languages

  • Increased capacity to express ideas

    • Features such as control structures and data structures can limit expression in a programming language.

    • Awareness of diverse programming features enhances software development capabilities.

    • Studying programming concepts promotes appreciation for valuable language features.

  • Improved background for choosing appropriate languages

    • Knowledge from experience in various languages aids in selecting suitable languages for new projects.

  • Increased ability to learn new languages

    • Programming languages evolve continuously, necessitating familiarity with fundamental concepts to ease the learning process.

  • Better understanding of implementation significance

    • Using a language intelligently involves understanding its design and available constructs, enhancing programming proficiency.

  • Overall advancement in computing

1.2 A Brief History of Programming Languages

  • Origins

    • Machine languages of the 1940s were the first programming languages.

    • Hundreds of languages have emerged since, with varying lifespan and impact.

    • Some languages have significantly influenced future designs.

  • Key Programming Languages Over Time

    • Machine Language - 1940s

    • Fortran - Late 1950s

    • Cobol - Late 1950s

    • Algol - 1960s

    • PL/I - 1960s

    • Pascal - 1970s

    • C - 1970s

    • C++ - 1980s

    • Java - 1990s

1.3 Introduction to Language Paradigms

  • Programming Languages - Tools for expressing algorithms between humans and computers.

  • Programming Paradigm - Method for representing algorithmic expressions suited for specific application domains.

Major Programming Paradigms

  1. Imperative Programming

    • Programs are sequences of steps executing calculations, retrieving inputs, or producing outputs.

    • Core constructs include assignments, loops, sequences, and conditionals.

    • Representative languages: Cobol, Fortran, C, C++.

  2. Object-Oriented Programming

    • Programs modeled as collections of interacting objects.

    • Fundamental concepts include object modeling, classification, and inheritance.

    • Representative languages: Smalltalk, Java, C++, Eiffel.

  3. Functional Programming

    • Programs consist of mathematical functions with defined inputs and results.

    • Interaction through functional composition, conditionals, and recursion.

    • Representative languages: Lisp, Scheme, Haskell, ML.

  4. Logic Programming

    • Programs declare logical outcomes, focusing on what rather than how.

    • Representative language: Prolog.

  5. Event-Driven Programming

    • Programs operate in continuous loops responding to unpredictable events.

    • Representative languages: Visual Basic, Java.

  6. Concurrent Programming/Parallel Programming

    • Programs consist of cooperating processes sharing information.

    • Representative languages: SR, High-Performance Fortran.

  • Multi-Paradigm Languages

    • Some languages support multiple paradigms (e.g., C++ is imperative and object-oriented).

1.4 Application Domains/Programming Domains

  • Scientific Computing

    • Focuses on fast, accurate calculations, typically using imperative programming. Common structures: arrays and matrices.

    • Modern languages: Fortran 90, C, High-Performance Fortran.

  • Business Applications

    • Includes payroll, accounting, and inventory systems.

    • Historically developed in Cobol, RPG, SQL; modern systems often use event-driven languages like Java.

  • Artificial Intelligence

    • Develops models for human-like intelligence and logical reasoning.

    • Languages: Lisp, Scheme, Haskell (Functional), Prolog (Logic).

  • Systems Programming

    • Designs and maintains core software, including operating systems and compilers.

    • Commonly employs imperative, parallel, and event-driven paradigms; C is predominant in Unix systems.

  • Web Software

    • Rapidly expanding area involving e-commerce and online systems.

    • Often employs object-oriented and event-driven paradigms, utilizing languages like Perl, JavaScript, PHP.

1.5 Language Evaluation Criteria

  • Readability

    • Ease of understanding programs, influenced by simplicity, orthogonality, control structures, and syntax.

  • Writability

    • Measure of how easily programs can be created; depends on language characteristics like abstraction and expressivity.

  • Reliability

    • Ability of a program to function as intended under all conditions. Language features contributing include type checking and exception handling.

  • Cost

    • Factors: programmer training, program writing, compilation, execution costs, and reliability costs.

    • Example: Java's rapid adoption due to free compiler availability.

1.6 Compilation Process

  • Overview

    • Compilation involves phases from source code to machine language execution.

    • Includes lexical analyzing, syntax analyzing, intermediate code generation, semantic analyzing, optimization, and code generation.

  • Phases

    • Lexical Analyzer: Segments the source code into units.

    • Syntax Analyzer: Constructs parse trees from lexical units.

    • Intermediate Code Generator: Converts to an intermediate representation.

    • Semantic Analyzer: Checks for type inconsistencies and other semantic errors.

    • Code Generator: Turns optimized intermediate code into machine language.

    • Linking: Combines user programs with necessary operating system components before execution.