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Introduction

Introduction. Instructor : Behnam Hajian bhajian@scs.carleton.ca. Introduction to Systems Programming - COMP 1002, 1402 . Objectives and syllabus. The objectives in this course is: To expose students to lower level systems interface only clearly visible via C.

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Introduction

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  1. Introduction Instructor : BehnamHajian bhajian@scs.carleton.ca Introduction to Systems Programming - COMP 1002, 1402

  2. Objectives and syllabus The objectives in this course is: • To expose students to lower level systems interface only clearly visible via C. • To further develop the ability to design programs with emphasis on the abstract view of data structures. • To get experience with the low-level implementation of data structures in C. • To experience programming in the Large

  3. Objectives and syllabus (continue) In this course you will learn: • The structure of a C program • How to use C/C++ compilers such as MinGW, Cygwin, GCC,… • How to execute a C program by platforms such as Borland C builder, Netbeans IDE, GCC,… • Variables and memory allocation • Type conversion, operators • control statements in C (if-then-else, while, for) • Function and Procedure, Call by Ref. and Call by Value, Input, Output

  4. Objectives and syllabus (continue) • Header files, System and Library Calls • Structs and complex data structure • Arrays and String (1-D, 2-D , n-D array) • Pointers and more on dynamic memory allocation, and de-allocation • Heap, Stack • Linked lists Manipulation

  5. Evaluation and… • 5 programming assignments : 50% • Final Exam: 50% Website: • Course material will be available on WebCT: look for the WebCT link from Carleton’s web site. Lectures: • Tuesday & Thursday 6PM - 9 PM @ 502 Southam Hall Office hours: • The hour before lecture. @ HP 5270 or HP 5336

  6. TA • Jimin Park • Email: jiminparky@gmail.com • Mon & Fri 2-4 PM

  7. TextBook References: • PPT slides are the most important resource for final exam. However, reading the textbook is highly recommended. TextBook: • C How to Program, 5th Edition, Harvey M. Deitel and Paul J. Deitel, both from Deitel & Associates, Inc.

  8. Computers • What is a computer? • A computational device • Logical decisions billions of times faster than humans • Hardware • keyboard, screen, disks, memory, CPU • Software • email, word processing, spreadsheets, OS

  9. Computer Organization • Input unit • keyboard, microphone • Output unit • screen, printer • Memory unit • Random Access Memory (RAM) • short-term, rapid access, low capacity warehouse • Read only memory ROM • Smaller amount of memory • stable when power off. • Stores enough code to boot system

  10. Computer Organization • Secondary storage unit • disks, tapes • long-term, slow access, high capacity warehouse • Central Processing Unit (CPU): Microprocessor (Intel Pentium, Motorola power PC): fetches machine instructions from memory, executes them • Arithmetic and logic unit (ALU) • calculations, comparisons • CU (Control Unit) • coordinator, administrator,

  11. Computer Architecture CPU Memory I/O Program Control Unit ALU

  12. Computer Architecture (cont.)

  13. Batch Processing one job at a time Multiprogramming many jobs simultaneously Timesharing multiple jobs, multiple users Personal computer (PC) standalone units Distributed computing workload distributed over networks Client/Server client machine provides user interface server machine provide computational power and storage location Computing Modes

  14. Programming Languages • Machine Language • machine/hardware dependent • Too hard to program in • Assembly Language • English-like operations (e.g., load, store, add) • High-level languages • single statement can accomplish substantial tasks • English-like statements with mathematical notations

  15. Why C? • Because we have to! C supports: • Many situations where it is only language or system available • Small, embedded systems, instrumentation, etc. • Many “low-level” situations that don’t have support for “high-level” languages • Operating systems, real-time systems, drivers

  16. Why not C? • C is very low-level • Data structures must be programmed “by hand” e.g. set,collection,… • Operations must be done out in “long hand” • No support for “object oriented” design • Marginal support for higher-level thought processes • Much, much harder to use than higher level languages/systems • Better alternatives available for almost all applications • Java, Python, Ruby, etc.– many CS situations • Matlab, SimuLink – physical modeling • LabView– instrumentation and control • Excel – accounting and statistics • SQL – billing and transactions • …

  17. What about C++? • Object-oriented thinking • Data abstractions, classes, objects, interfaces • Operator overloading • Inheritance • Lots of other good stuff • … • Backward compatible with C • To some extent • Allows programmer to get close to hardware when needed • Allows programmer to get close to data representation when needed • Not platform independent (like Java) • Still need to be conscious of memory management • …

  18. C Program Development Environment Standard Steps • Edit • Preprocess • Compile • Link • Load • Execute

  19. A Short History • In the beginning … • Machine language • Assembly language • One line per machine instruction • So “high level” languages were invented • Non-recursive:– Fortran, Cobol • Recursive:– Algol, Lisp, Snobol, PL/1, etc. Really primitive!Too difficult for big projects Too advanced! Too much infrastructure for operating systems, control systems, manykinds of projects

  20. C: History • Developed in the 1970s – in conjunction with development of UNIX operating system • When writing an OS kernel, efficiency is crucial This requires low-level access to the underlying hardware: • e.g. programmer can leverage knowledge of how data is laid out in memory, to enable faster data access • UNIX originally written in low-level assembly language – but there were problems: • No structured programming (e.g. encapsulating routines as “functions”, “methods”, etc.) – code hard to maintain • Code worked only for particular hardware – not portable

  21. C: Characteristics • C takes a middle path between low-level assembly language… • Direct access to memory layout through pointer manipulation • C is Concise syntax, small set of keywords • Is also a high-level programming language like Java: • Block structure • Some encapsulation of code, via functions • Type checking (pretty weak)

  22. C: Dangers • C is not object oriented! • Can’t “hide” data as “private” or “protected” fields • You can follow standards to write C code that looks object-oriented, but you have to be disciplined – will the other people working on your code also be disciplined? • C has portability issues • Low-level “tricks” may make your C code run well on one platform – but the tricks might not work elsewhere • The compiler and runtime system will rarely stop your C program from doing stupid/bad things • Compile-time type checking is weak • No run-time checks for array bounds errors, etc. like in Java

  23. Questions?

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