Chapter 1 – Overview of Programming and Problem Solving
Programming – aka coding – process of designing, writing, testing and debugging source code /
computer programs
Programming does require expertise in a programming language and algorithm
development
Computer – machine that receives input, processes input based on programmed instructions and
produces output
Semester goal:: teach/learn programming
Process of developing a program:
Development life cycle – process broken into 3 parts:
Problem-solving phase
Implementation phase
Maintenance phase
Problem-solving phase consists of
Analysis – look closely at the problem to gain an understanding of it – if it is
complex, it will require breaking down into smaller pieces
Specification – documentation that is produced after the problem is analyzed –
it describes how the problem will be solved
Developing an Algorithm – this involves creating a detailed, step-by-step solution
to the problem or subproblems in a finite amount of time (this is really the
hard part!) – expressed in English
ex1:: Algorithm for finding the perimeter and area of a rectangle
ex2:: Algorithm for finding total tax and amount due of an item given:
Homework:
selling price of item, 4% sales tax, 10% luxury tax
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Verify Correctness of the solution – desk checking the solution – tracing the
WU #1, #2
algorithm
CSFU #2,3,4,5
ex1:: Tracing algorithm for computing salesperson’s salary (handout)
This phase is iterative and should not be skipped!
Implementation Phase consists of
Writing the program – translating the algorithm into a programming language
such as C++ (this gets easier with practice!)
ex1:: A sample program to find perimeter and area of a rectangle
Programming Language – set of rules, symbols and special words used to
construct a program
Testing the program – compiling and executing the program to locate errors in
using the language and errors in the output – finding errors in the output
requires a set of test cases – sample input to the program checking all
possible execution paths
Maintenance Phase consists of
Using the program in the environment is was intended to run in
Updating the program as requirements change – modifications may need to be
made to correct errors as well
Waterfall model of software development – but there are other models
Documentation – used to identify the program and explain its use – written in English and
embedded in the code – explains complex/tricky code – can also be external to the code –
must be easy to read and understand!
Debugging – process of identifying and eliminating defects/errors/bugs in a program (Where did
this term come from?)
Data vs. Information – data are raw facts – eventually must be represented in a form that the
computer can use – information is data that has been processed/structured/presented in a
form that makes it useful
ex1:: Data → 92710
Information → 9/27/10 – date of first exam
$92,710 – average starting salary of a database administrator
92710 – zip code for Irvine, CA
Programming Languages – definition above, but they have evolved over time:
Machine language – instructions and data are represented in binary digits arranged in a
form a particular computer understands – eventually all programs must be
converted to this form in order to be executed
Assemblers – converts assembly language program into machine language
assembly language is a programming language in which the machine language
instruction was replaced with a mneumonic (easy to remember name)
Compilers – convert high-level languages into machine code – program instructions are
getting even easier to understand – translation for entire program first, then
executed
Interpreters – also converts high-level languages into machine code, but translates and
executes each line one at a time
Preparing a program for execution
To start – program entered using a text editor and stored as a file – source program
the source program then translated using a compiler and if no syntax errors –
object program created, which is the high-level program translated into machine
code
Then – since most programs use environments that contain precompiled components (ie
math functions) that are stored in libraries, a linker (or linking) combines the
object program with the precompiled components from the library
Finally – at this point, the program can be executed – executing the program causes the
final object file to be loaded into memory and appropriate hardware resources are
made available to the program
Source Program
entered with
Editor
Source File
We will practice
this in the first inclass lab
Source Program
translated by
Compiler
Object File
Object Program
linked with
Libraries
Object File ready
for Execution
Control Structures within a program– tell us which order instructions will be executed or
evaluated
Sequence – one after the other
Selection – depends on the “truth” of a condition
Iteration – repeats a series of instructions – aka looping
Subprogram – consists of a series of instructions that are always executed together when
invoked
Instructions are based on what computer can perform: transfer of data, input data from
device, output data to device, store data to memory/secondary storage, retrieve data from
memory/secondary storage, compare two values, perform arithmetic operations
Taking a look inside the computer system – hardware and software together make up the system
Hardware – physical components
Memory – RAM temporary storage for program and data
CPU – processing unit – responsible for program execution
Control Unit – fetches instruction from memory then translates
into control signals
Arithmetic/Logic Unit – executes control signals utilizing appropriate resources
Peripheral devices – any device attached to computer
Homework:
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EPE #1 - #12
Auxiliary storage devices/Secondary storage devices – a more permanent storage
area for data and instructions
Input devices – accepts data to be processed
Output devices – presents data that has been processed
How many peripheral devices can you name?
Software – programs – usually where most $ spent!
System Software – aka operating system – programs that manage the computer’s
resources – name some? – usually comes with a basic editor
Programming Languages – already discussed above – can you name some?
Application Software – programs written to solve a particular problem – can you name
some?
Most software designed with a particular user interface in mind – users may have a
windows environment or they may have to enter commands directly on the command line
– most are interactive – a requested operation gets immediate response
Network – many computers joined together in order to share resources (storage, printers,
processing capabilities, files, communication).
Ethics in Computing – computers have had profound effect on society and vice versa – every
profession has a set of ethics that define responsibilities of practitioner
Software Piracy – unauthorized copying of software for personal use or use by others
without permission of creator
Privacy of Data – should not take advantage of access to confidential data
Use of resource – should not gain unauthorized access to any computer – should not
develop/disseminate viruses
Tips for problem solving: ask questions to clarify problem statement and try not to reinvent the
wheel – if you have seen a similar problem, repeat the solution
Solve by analogy – maybe the problem being solved might be easier if the solution to
another problem was explored – the other problem need not be a computer problem!
Divide and conquer – break problem into smaller pieces that can be solved more quickly
Building-block – determine if a large problem can be solved by smaller problems that
already have a solution
Merging – combine existing solutions on a step-by-step basis
If faced with a mental block – try writing the problem down in own words
When developing an algorithmic solution, keep in mind the list of things the computer
can do (from above) and repeated here – base solution on these operations:
Instructions are based on what computer can perform: transfer of data, input data
from device, output data to device, store data to memory/secondary storage, retrieve data
from memory/secondary storage, compare two values, perform arithmetic operations