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Computer Programming2
Course materials
Required textbook– C++: Introduction to Computing, 3rd Edition, by Adams &
Nyhoff , Prentice-Hall 2003 Other References textbooks
– B. Stroustrup: The C++ Programming Language (3rd edition). Addison Wesley Longman, 1997.
– The C++ reference site: http://www.cplusplus.com/
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Course objectives
Learn fundamentals of Procedural Programming (control structures and modularity), applicable to most languages: Fortran, Basic, Perl, Assembler, etc.
Learn to implement algorithms to solve problems by writing programs in the programming languages: C and C++.
Introduce the concepts required for Object-Oriented Programming.
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Your participation
Midterm 15%
Quizzes and class participation
10%
Assignments (2) 15%
Lab 30%
Final Exam 30%
Total 100%
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Your feedback
Teaching/learning is interactive– two-way communications
Let me know– what you think about lectures, projects, labs, exams, topics,
…– What you want to know or probe further
You can reach me– in class, during office hours, by email/phone
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Agenda of the course
Overview of computer science field Basic Programming Structure Operators and build in functions Control flow (if, switch, while, for) User defined functions Arrays & strings Pointers Object-Oriented Programming Files and other I/O operations
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First things First: How to Study
There are no such things as– “I am stupid. I can never understand this material”– “The others are smarter than me. I am just a loser.”– “My capacity is limited, and my brain can’t handle it.”
Everyone of us is capable of achieving anything given– Enthusiasm– Perseverance, especially in CG– Patience, especially in CG– Time organization– Suitable style of learning
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First things First: How to Study
The killer of them all: Procrastination– Excuses for not studying and doing your homework:
“I can’t study now because I have to get a haircut.” “I can’t do the project because I have other projects.” “I can’t review the CS373 lectures because I have to review only
for this coming exam.” “It is Okay to leave things until the day of exam.”
– The cure: “Do not leave the work of today until tomorrow for tomorrow has its
own work.” Reward yourself: “After I am done with this, I should get a nice
haircut.” Start with things that you feel good at.
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First things First: How to Study
How to be a good student– People think and learn differently:
Eyes: Visual learner Ears: Auditory learner Order: sequential learner Images: global learner Doing: kinesthetic learner
– Find your own style of learning Write sequential notes Use mind-map technique Draw images Explain loudly the lecture to yourself The read the lecture while walking Write and run the code to see how things work
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How to be a good student
Find your optimal style of learning Do not miss a single lecture Be active during the lecture:
– Write notes– Ask questions
Study your notes– Just after the lecture– At least three times during the week of the lecture– Once after two weeks– Once after three weeks and so on
Organize your time– Do not over-study for a course at the expense of the other courses– Try to give each course an amount of time every day– Do not leave the review and the project until one day before the deadline– Do not procrastinate!
Use office hours as much as possible Take time to sharpen your axe
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Overview
Computers have two kinds of components: Hardware – physical devices such as
– CPU– memory– storage devices
Software – programs such as– Operating system– applications– utilities
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Hardware
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Hardware
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Hardware: CPU
Central Processing Unit (CPU):– the “brain” of the machine– Circuitry that performs arithmetic and logical ML
statements
CPU measurement – Speed in gigahertz (109 clock-ticks per second)
Examples– Intel Pentium, AMD K6, Motorola PowerPC, Sun
SPARC,
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Storage
Random Access Memory (RAM)– “Main” memory, which is fast, but volatile...– Analogous to a person’s short-term memory.– Many tiny “on-off” switches
“on” is represented by 1, “off” by 0.
Each switch is called a binary digit, or bit.– 8 bits is called a byte.– 210 bytes =1024 bytes is called a kilobyte (1K)– 220 bytes is called a megabyte (1M).
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Storage
Secondary Memory (Disk):– Stable storage using magnetic or optical media.– Analogous to a person’s long-term memory.– Slower to access than RAM.
Examples: – floppy disk (measured in kilobytes (210 bytes))– hard disk (measured in gigabytes (230 bytes))– CD-ROM (measured in megabytes (220 bytes)), ...
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Input and Output
Input devices– Instructions and data must be encoded in binary
form and transmitted to the CPU
Examples:– keyboard– mouse, trackball, joystick– scanner– audio, video capture boards
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Input and Output
Output devices– Convert data from binary to another form
Examples– monitors, printers– sound, video– robotics control
Communication between CPU and peripheral devices is through ports– Ports communicate via the system bus
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Hardware: the Bus
The Bus:– Connects CPU to other hardware devices.– Analogous to a person’s spinal cord.
Speed measured in megahertz (millions of clock-ticks per second)– Typically much slower than the CPU...– The bottleneck in most of today’s PCs.
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Hardware: Cache
Access speed of RAM – Faster than accessing secondary memory– Still quite slow, relative to the rate at which the CPU runs.
Solution:– Add a fast cache memory to the CPU– Store recently used instructions and data
Assumption:– These instructions/data were needed recently– They will be needed again in the near future.
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Hardware: Summary
Putting the pieces together:
CPU
Bus
MainMemory
SecondaryMemory
cache
Program storage– Long-term in secondary memory– Loaded into main memory to run– From which the CPU retrieves and executes their statements.
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Software: OS
Operating system (OS)– Loaded from secondary memory into main memory
when the computer is turned on,– Remains in memory until the computer is turned off.
DiskRAMCPUCache
Bus
OS
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Software: OS
OS acts as the “manager” of the system, – Making sure that each hardware device interacts
smoothly with the others.
Provides an interface – Enables user to interact with the computer, – Awaits user input if no application is running.
Examples: MacOS, Windows-95, Windows-NT, UNIX, Linux, Solaris, ...
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Software: Applications
Applications are non-OS programs – Perform some useful task– Including word processors, spreadsheets,
databases, web browsers, C++ compilers
Example C++ compilers/environments: – CodeWarrior (MacOS, Win95, WinNT, Solaris) – GNU C++ (UNIX, Linux)– Turbo/Borland C++ (Win95, WinNT)– Visual C++ (Win95, WinNT)
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Software: User Programs
Programs that are neither OS programs nor applications are called user programs.
User programs are what you’ll be writing in this course.
A user program is supposed to solve a problem!– Is the problem solvable?– Is the problem efficiently solvable?
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What is Programming?
Computer Program– A sequence of statements that instruct a computer in how to
solve a problem. Programming
– The act of designing, writing, and maintaining a program Programmers
– People who write programs Hackers
– People who enjoy exploring the details of computers and how to stretch their capabilities
– Do you want to be one?
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What kinds of statementsdo computers understand?
A computer only understands machine language statements.
Characteristics of machine language– A sequence of ones and zeros – Cause the computer to perform a particular action,
such as add, subtract, multiply, ...
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Machine Language (ML)
ML statements – Stored in a computer’s memory
Computer memory is a sequence of switches. – an “on” switch is represented by 1, – an “off” switch is represented by 0.
ML thus appears to be binary (base-2):
0010111010110101
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Early Computers
... required a programmer to write in ML... Problem
– Easy to make mistakes!– Such mistakes are hard to find!– Not portable -- only runs on one kind of machine!
Programming was very difficult!
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A Bright Idea
Devise a set of abbreviations (mnemonics) corresponding to the ML statements
Create a program (the assembler) to translate them into ML.
ADD 34, R1MOVE R1,1200CMPR R1, R2
100111001110010110100110110111
Assembler
Assembly languagestatements (mnemonics)
Machine language statements
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Advantages and Disadvantages
More natural than binary.
Much easier to read programs
Much easier to find and fix mistakes
Still not portable to different machines
Each machine had its own set of mnemonics
Each had its own assembler
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High Level Languages
Improvement on assembly language– Devise a set of statements that are close to human
language (if, while, do, ...)– Create a program to translate them into ML.
The set of statements is called a high-level language (HLL)
The translation program is called a compiler. A linker is sometimes needed! Sometimes we use interpreters instead of
compilers!
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Compiler Versus Interpreter
Source code Compiler Machine language
A Compiler translates a file written in a high-level language into a machine language file that can be executed on the computer.
An interpreter executes each high-level statement directly. On fly, the interpreter translates the statement to the corresponding machine language instructions and executes/runs them.
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Contrast Assembler and HLL Compiler
Assembler translates one mnemonic into one ML statement
Compiler translates one HL statement into several ML statements
1010110011110101
0000000000010000
0010111010110101
0000000000010010
0010111011111101
0000000000010100
z = x + y; Compiler
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Advantage of HLLs
Programs are easier to read Errors are easier to find Programs are portable from one computer to
another– Assumes the language is standard– Just create a new compiler which does the
translation into the correct ML
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Objectives in Programming A program should solve a problem:
Correctly Efficiently Readably In user-friendly
fashion
It actually solves the problem Without wasting time or space Understandable by another
person In a way that is easy for its user
to use
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Summary of "Levels" of Computer Languages
Low levelML in binary language
Medium Level Assembly language
High Levelas in C++
Hard to read, not portable
Mnemonics, easier to read, still not portable
Reads like English and algebra, portable
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Putting It All Together
Programs and applications that are not running are stored on disk.
App
DiskRAMCPUCache
Bus
OS
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Putting It All Together
When you launch a program– OS controls the CPU – Loads the program from disk to RAM.
App
DiskRAMCPUCache
Bus
OS
App
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The OS then relinquishes the CPU to the program, Application program begins to run.
App
DiskRAMCPUCache
Bus
OS
AppApp
Putting It All Together
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The Fetch-Execute Cycle
CPU repeatedly fetches the next instruction (from memory / cache), Executes it Stores any results back to memory.
That’s all a computer does: fetch-execute-store, millions of times each second!
App
DiskRAMCPUCache
Bus
OS
AppApp
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First program: Hello World!
#include <iostream>
using namespace std;
int main() {
cout << “Hello World!”<<endl;
return 0;
}
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First program: Hello World!
Save the previous program as hello.cpp Compile it:
– g++ -o hello hello.cpp– Build button
Run it:– hello– Run button
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First Interesting Problem
Write a program that computes the volume of a sphere with a radius specified by the user.
To do in class!
