COMP 1020:
Structured
Programming (2)
Instructor: Prof. Ken Tsang
Room E409-R11
Email: kentsang@uic.edu.hk
1
TA information
Mr Fu Song-feng
付嵩峰
Room E409
Tel: 3620630
songfengfu@uic.edu.hk
2
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
3
Tutorials
• One hour each week
• Time & place to be announced later (we
need your input)
• More explanations
• More examples
• More exercises
4
How is my final grade
determined?
•
•
•
•
Lab works
Project
Quizzes
Final Examination
15%
20%
15%
50%
5
UIC Score System
6
Grade Distribution Guidelines
7
Reference
“The C Programming Language”
by Brian W. Kernighan & Dennis M. Ritchie
Published by Prentice-Hall in 1988
ISBN 0-13-110362-8 (paperback)
8
Reference books
• Practical C Programming
by Steve Oualline, O’Reilly&Associates
• Practical C++ Programming
by Steve Oualline, O’Reilly&Associates
C Programming: A Modern
Approach by K.N. King
http://www.cprogramming.com/tutorial/c/lesson
9
15.html
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.
10
The McKinsey Global Institute:
11
How Companies Learn Your Secrets
By CHARLES DUHIGG
Published: February 16, 2012
12
Lecture 1
Introduction: basic
knowledge of computer
hardware and software
Structured Programming
Instructor: Prof. K. T. Tsang
13
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
14
Basic components of a computer
Communication devices
(modem,
internet connection)
Storage Devices
(hard-disk, DVD)
D
D
Memory
(RAM)
D
Input devices
(mouse,
keyboard,
microphone)
D
CPU
(Central Processing Unit)
I
Output devices
(monitor,
printer,
speaker)
D = data
I = information
15
CPU - central processing unit
processor/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.
16
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. 17
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.
18
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.
19
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.
20
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.
21
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.
22
Memory Hierarchy
Inboard memory
Outboard storage
Off-line storage
Registers
fastest
Cache
Main memory
magnetic disk
CD-ROM
CD-RW
DVD
magnetic tape
Network-attached storage (NAS)
23
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.
24
Inboard memory
Registers
Memory bus
ALU
Main memory
(RAM)
Cache memory
CPU
25
Registers -- a small amount of very fast memory
used to speed the execution of programs by
providing quick access to commonly used
values—typically, 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 memory—a 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.
26
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.
27
Inboard memory
L2 Cache
Registers
Memory bus
ALU
L1 Cache
Memory bus
CPU
Main memory
(RAM)
28
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.)
29
The Computer Level Hierarchy
30
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
31
Layered-view of a computing system
End user
Programmer
Application programs
Operating system
Designer/programmer
utilities
Operating system
Computer hardware
32
33
Machine and Assembly Language
34
What an assembler does
35
High Level Language
AREA = HEIGHT * WIDTH
36
High Level Language
37
Construction of a Program
38
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.
39
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.
40
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 Microsoft’s 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").
41
History of C & C++
C&
42
How C & C++ work?
43
Difference between C and C++
(including C)
44
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”.
45
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.
46
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.
47
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.
48
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.
49
50
51
Programming Tools (1)
52
Programming Tools (2)
53
Programming Tools (3)
54
Wrappers or IDEs
55
Programming with Wrappers or IDEs
Text editor
56