COMP 1020: Structured Programming (2)

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COMP 1020Structured Programming (2)

• Instructor Prof. Ken Tsang
• Room E409-R11
• Email kentsang_at_uic.edu.hk

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TA information

• Mr Fu Song-feng ???
• Room E409 Tel [phone]
• songfengfu_at_uic.edu.hk

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Web-page for this class

• Watch for announcements about this class and
• download lecture notes from
• http//www.uic.edu.hk/kentsang/comp1020/comp1020.
  htm
• Or from this page
• http//www.uic.edu.hk/kentsang/
• Or from the Ispace

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Tutorials

• One hour each week
• Time place to be announced later (we need your
  input)
• More explanations
• More examples
• More exercises

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How is my final grade determined?

• Lab works 15
• Project 20
• Quizzes 15
• Final Examination 50

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UIC Score System
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Grade Distribution Guidelines
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Reference

• The C Programming Language
• by Brian W. Kernighan Dennis M. Ritchie

Published by Prentice-Hall in 1988 ISBN
0-13-110362-8 (paperback)
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Reference books

• Practical C Programming
• by Steve Oualline, OReillyAssociates
• Practical C Programming
• by Steve Oualline, OReillyAssociates
• C Programming A Modern Approach by K.N. King
• http//www.cprogramming.com/tutorial/c/lesson15.ht
  ml

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Why do we have to learn programming?

• Big Data
• There is a lot of data around us, because
• It is cheap to obtain store
• It is difficult to capture, store, manage, share,
  analyze and visualize data without using
  computational tools.

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The McKinsey Global Institute
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How Companies Learn Your Secrets
By CHARLES DUHIGG Published February 16, 2012
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• Lecture 1
• Introduction basic knowledge of computer
  hardware and software
• Structured Programming Instructor Prof. K. T.
  Tsang

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Computer -- a machine for manipulating data
according to a list of instructions known as a
program.

• Supercomputer, Mainframes
• Workstations, Servers
• Personal computers, Laptops
• Embedded computers Cell phones, Digital cameras,
  Fighter aircrafts, robots

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Basic components of a computer
D data I information
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CPU - central processing unitprocessor/central
processor

• The CPU is the brains of the computer, where most
  calculations take place and determines the power
  of the system.
• In personal computers and small workstations, the
  CPU is housed in a single chip called a
  microprocessor. More powerful computers have
  more than one processors.
• Typical components of a CPU are
• The arithmetic logic unit (ALU), which performs
  arithmetic and logical operations.
• The control unit (CU), which extracts
  instructions from memory and decodes and executes
  them, calling on the ALU when necessary.
• The Registers, temporarily hold instructions and
  data.

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Machine instruction cycle(also called machine
cycle, instruction cycle)

• The time period during which one instruction is
  fetched from memory and executed when computer is
  given an instruction in machine language.
• Four stages of an instruction cycle
• Fetch the instruction from memory. This step
  brings the instruction into the instruction
  register, a circuit that holds the instruction so
  that it can be decoded and executed.
• Decode the instruction.
• Execute the instruction.
• Store the result in memory.
• Steps 1 and 2 are called the fetch cycle and are
  the same for each instruction. Steps 3 and 4 are
  called the execute cycle and will change with
  each instruction.

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Computer memory (or casually memory) --computer
components/devices that retain data/programs for
some interval of time.

• Computer storage provides one of the core
  functions of the modern computer, that of
  information retention. It is one of the
  fundamental components of all modern computers.

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Von Neumann Architecture for computer

• CPU
• Main memory
• I/O modules move data between computer and its
  external environment, including secondary memory
  devices (e.g. disks) communication equipments and
  terminals.
• System buses move data between CPU, main memory
  and I/O devices.

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Memory/ Storage

• Memory usually refers to a form of solid state
  storage known as random access memory (RAM) and
  sometimes other forms of fast but temporary
  storage.
• Storage more commonly refers to mass storage
  optical discs, forms of magnetic storage like
  hard disks, and other types of storage which are
  slower than RAM, but of a more permanent nature.

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RAM a data storage formats and equipment that
allow the storing data to be accessed in any
order that is, at random, not just in sequence.

• In contrast, other types of memory devices (such
  as magnetic tapes, disks, and drums) can access
  data on the storage medium only in a
  predetermined order due to constraints in their
  mechanical design.

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RAM

• RAM in a computer is considered main memory
  (primary storage). The arithmetic and logic unit
  can very quickly transfer information between a
  processor register and locations in main storage
  (memory addresses). In modern computers, RAM is
  directly connected to the CPU via a "memory bus"
  and a "data bus". In general, a faster memory bus
  means higher processing speeds and a faster
  computer.
• RAM is also volatile, losing the stored
  information in an event of power loss, and quite
  expensive.
• This type of RAM is usually in the form of
  integrated circuits (IC). Most personal computers
  have slots for adding and replacing memory chips.
  
• A location in memory is identified by its
  address. The data hold in a memory address can be
  changed, but the address itself remains the same.

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Memory Hierarchy

• Inboard memory Registers fastest
• Cache
• Main memory
• Outboard storage magnetic disk
• CD-ROM
• CD-RW
• DVD
• Off-line storage magnetic tape
• Network-attached storage (NAS)

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Three kinds of Primary memory

• Processor registers are internal to the CPU.
  Registers contain information that the arithmetic
  and logic unit needs to carry out the current
  instruction. They are technically the fastest of
  all forms of computer storage.
• Cache memory is a special type of internal memory
  used by many CPUs to increase their performance.
• Main memory contains the programs that are
  currently being run and the data the programs are
  operating on.

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Inboard memory
ALU
Registers
Main memory (RAM)
Memory bus
Cache memory
CPU
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Registers -- a small amount of very fast memory
used to speed the execution of programs by
providing quick access to commonly used
valuestypically, the values being calculated at
a given point in time.

• Most, but not all, modern computer architectures
  operate on the principle of moving data from main
  memory into registers, operating on them, then
  moving the result back into main memorya
  so-called load-store architecture.
• All data must be represented in a register before
  it can be processed. For example, if two numbers
  are to be multiplied, both numbers must be in
  registers, and the result is also placed in a
  register.
• The number of registers that a CPU has and the
  size of each (number of bits) help determine the
  power and speed of a CPU. For example a 32-bit
  CPU is one in which each register is 32 bits
  wide. Therefore, each CPU instruction can
  manipulate 32 bits of data.

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Cache -- a block of memory for temporary storage
of data likely to be used again

• A simple definition of Cache A temporary
  storage area where frequently accessed data can
  be stored for rapid access.
• Once the data is stored in the cache, future use
  can be made by accessing the cached copy rather
  than re-fetching or re-computing the original
  data, so that the average access time is lower.

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Inboard memory
L2 Cache
ALU
Registers
Memory bus
L1 Cache
Memory bus
Main memory (RAM)
CPU
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Software Basics

• Computer Hardware Software
• Software
• Application software
• Address users' specific needs in the real world
• word processing, music software, image editing,
  games, database programs, inventory control
  systems, etc.
• System software
• Operating system
• Device drivers
• Utilities
• Programming software tools (compilers, debuggers,
  etc.)

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The Computer Level Hierarchy
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Operation System -- A set of programs to
coordinate all activities of among computer
hardware devices, to exploit resources provided
by one or more processors.It is a layer of
software to hide all the details of machine
complication from system users. All high level
programming activities are performed on top of
the OS.

• Examples
• DOS, Window, Window XP
• UNIX, Linux
• Mac OS

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Layered-view of a computing system
End user
Programmer
Application programs
Operating system Designer/programmer
utilities
Operating system
Computer hardware
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Machine and Assembly Language
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What an assembler does
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High Level Language
AREA HEIGHT WIDTH
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High Level Language
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Construction of a Program
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Computer programming

• (or simply programming or coding) is the process
  of writing a set of commands or instructions that
  can later be compiled and/or interpreted and then
  transformed to an executable that an electronic
  machine can execute or "run".
• Programming requires mainly logic, but has
  elements of science, mathematics, engineering,
  and many would argue art.
• Programming requires the use of a programming
  language that the computer can understand.
• In software engineering, programming
  (implementation) is regarded as one phase in a
  software development process.

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Programming Language

• The only programming language a computer can
  directly execute is machine language (sometimes
  called "machine code").
• Originally all programmers worked out every
  detail of the machine code (machine dependent),
  but this is hardly ever done anymore.
• Instead, programmers write high-level source
  code, and a computer (by running a compiler, an
  interpreter or occasionally an assembler)
  translates it through one or more translation
  steps to fill in all the details, before the
  final machine code is executed on the target
  computer.

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Programming Language (2)

• In some languages, an interpretable byte-code is
  generated, rather than machine language.
  Byte-code is used in the popular Java by Sun
  Microsystems, as well as Microsofts recent .NET
  family of languages and Visual Basic previous to
  the .NET version.
• Different programming languages support different
  styles of programming. Part of the art of
  programming is selecting one of the programming
  languages best suited for the task at hand.
  Different programming languages require different
  levels of detail to be handled by the programmer
  when implementing algorithms, often in a
  compromise between ease of use and performance (a
  trade-off between "programmer time" and "computer
  time").

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History of C C
C
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How C C work?
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Difference between C and C
(including C)
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Procedural Programming

• specifying the steps the program must take to
  reach the desired state
• based upon the concept of procedure calls
• Simple sequential or unstructured programming in
  many situations which involve moderate complexity
  will lead to so-called spaghetti code.

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• Structured programming (using C)can be seen as a
  subset or sub-discipline of procedural
  programming, one of the major programming
  paradigms (other paradigm object oriented
  programming with C)
• It is most famous for removing or reducing
  reliance on the GOTO (or "go to") action.

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Benefits of structured programming

• The ability to re-use the same code at different
  places in the program without copying it.
• An easier way to keep track of program flow than
  a collection of "GOTO" or "JUMP" Actions (which
  can turn a large, complicated program into
  so-called spaghetti code).
• The ability to be strongly modular.

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Low-level structure

• At a low level, structured programs are composed
  of simple, hierarchical program flow structures.
  These are regarded as single Actions, and are the
  same time ways of combining simpler Actions,
  which may be one of these structures, or
  primitive Actions such as assignments or
  procedure calls. Three common types of structure
  were concatenation, selection, and repetition.
• "Concatenation" refers to a sequence of Actions
  executed in order.
• In "selection", one of a number of Actions is
  executed depending on the state of the program.
  This is usually Expressed with keywords such as
  if..then..else..endif, switch, or case.
• In "repetition" a Action is executed until the
  program reaches a certain state or applied to
  every element of a collection. This is usually
  Expressed with keywords such as while, repeat,
  for or do..until. Often it is recommended that
  each loop should only have one entry point (and
  in the original structural programming, also only
  one exit point), and a few languages enforce this.

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High-level structure

• Coders should break larger pieces of code into
  shorter subroutines (functions, procedures.
  methods, blocks, or otherwise) that are small
  enough to be understood easily.
• In general, programs should use global variables
  sparingly instead, subroutines should use local
  variables and take arguments by either value or
  reference. These techniques help to make isolated
  small pieces of code easier to understand without
  having to understand the whole program at once.

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Programming Tools (1)
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Programming Tools (2)
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Programming Tools (3)
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Wrappers or IDEs
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Programming with Wrappers or IDEs
Text editor