CS1061 C Programming (5 credits) Lecturer: Adrian O’Riordan Contact: is office is 312, Kane Lectures: 24 in total Kane Building O’Rahilly Building Practicals:Organised later in year (12 hours) Assessment: Total Marks 100: End of Year Written Examination (1½hr paper) 80 marks; Continuous Assessment 20 marks.

Objectives Module Objective: To teach fundamental techniques of computer programming using the C language. Module Content: Principles of programming: algorithms, design and specification; testing and debugging. Fundamentals of C programming: data types; operators; expressions; control structures; console and file i/o. Program structure: functions, recursion, standard libraries. Aggregate data types: arrays; pointers; strings; records. Dynamic data structures: allocation; deallocation; memory management; list structures.

Reading material The Boole library has a number of good books on C: C for scientists and engineers / Richard Johnsonbaugh, Martin Kalin, Prentice Hall, A book on C : programming in C / Al Kelley, Ira Pohl, Addison- Wesley, C : how to program / H. M. Deitel, P. J. Deitel, Prentice-Hall, There are also a number of good tutorials freely available on the WWW.

The computer The primary components of a computer are the central processing unit (CPU), arithmetic and logic unit, main memory, and various input/output devices. This is the hardware. The programs that run on a computer are the software. The CPU controls the execution of these programs using its own internal clock. A computer program is a sequence of instructions issued to a computer. The instructions are stored in the computer’s memory.

Instructions The instructions are read from memory one-by-one by the computer processor. Main memory is fast to access. Secondary storage, i.e. hard disks, is typically slower to access but much larger in capacity. Program instructions are read and executed extremely quickly by a computer compared to human speeds. (For example, an instruction (executed in a single clock cycle) on a 3GHz processor could potentially be executed in 0.33 nanoseconds. Programs often perform input (from keyboard/mouse) and output (to terminal) functions in addition to executing instructions. This tends to be much slower.

Programming languages Programs are written in a programming language. The earliest programming languages were all low-level such as machine code and assembler. Low-level languages are hard and tedious to write but tend to execute quickly. High-level languages have a more structured form and English-like syntax. A program called a compiler (or interpreter) is used to translate the high-level source into machine code that the computer can understand. The development of higher-level languages greatly increased programming productivity.

Examples of Languages Example taken from Dietel and Dietel 1.Machine language - strings of numbers giving machine specific instructions Assembly languages LOAD BASEPAY ADD OVERPAY STORE GROSSPAY 3.High-level languages - Code similar to everyday English grossPay = basePay + overTimePay

Problem Solving Programming is a form of problem solving. Faced with the requirement to implement a solution to a problem, the programming has to translate the problem description into a language a computer can understand. Though requirements may be expressed as clearly, succinctly and unambiguously as possible, there is still a lot of scope for errors, omissions and inconsistencies. Implementation can introduce a new layer of errors. Thus software development has a reputation for being hard, and cannot be fully automated. A key idea in computer science is that of an algorithm (see later)

Introducing C C is a high-level language that also retains many features of low-level programming. C is very fast – as fast as machine code on many platforms. Thus C is the first choice for developers concerned with performance, for example in applications such as embedded systems, real time systems, and reconfigurable hardware. C was probably the world’s most widely used programming language until more recently being challenged by the rise of Java. A lot of modern programming languages, such as C++ and Java, are influenced and retain a similar syntax to C.

Advantages of C Widely adopted industry standard Very fast Supports structured programming (see later) Relatively small number of commands and keywords Powerful pointer-based implementation (see later) Low-level (bit-wise) operations (see later) Supports dynamic memory allocation (see later) Code libraries available (See later)

Background Context History C was developed at Bell labs. c by Martin Ritchie based on Martin Richard’s BCPL (1967) and Ken Thompson’s B language (1970). C was initially used predominantly for systems programming, but is now very much a general-purpose language. It has been ported to a large number of platforms including Windows, Macintosh and many flavours of UNIX. Standardisation Initially many slight variations of C existed, and were incompatible so a committee was formed to create a unambiguous, machine- independent definition. ISO Standard created in 1989 (most widely used) and updated in 1999 (C99).

Related Languages C++ - The C++ programming language was derived from C and has object-oriented functionality with C-like syntax. Objective-C - Objective-C is a very "thin" layer on top of, and is a strict superset of C Java and C#- Modern languages that retain the basic C syntax