computer programming introduction ppt.ppt

Introduction to Programming
and Problem Solving
1

Parts of a Computer System:
• Hardware: Electronic Devices
• Software: Instructions and Computer
Programs

Hardware
• Input : Keyboard, Mouse
• System unit:
– Random Access Memory (RAM)
– Central Processing Unit (CPU)
• Output: Monitor, Printer
• Secondary Storage: Disk Drive

Software
 Instructions for the hardware.
 Actions to be performed
 A set of instructions is called a program.
 Driving force behind the computer
 Without a program – What is a computer?
▪ Collection of Useless Hardware

CPU
• The central processing unit (CPU)
• The “brain” of a computer
• Retrieves instructions from
memory and executes them.

Memory (RAM)
 Stores data and program instructions for CPU to
execute
 A program and its data must be brought to memory
before they can be executed
 Stores intermediate and final results of
processing.
 Volatile: Contents are erased when computer is
turned off or reset.
 A memory unit is an ordered sequence of bytes,
each holds eight bits. A byte is the minimum
storage unit. No two data can share or split the
same byte.

Storage Devices
• Hard Drives, CDs/DVDs, Flash Drives, etc.
• Non-Volatile or Permanent Storage
• Programs and data are permanently stored on
storage devices and are moved to memory
when the computer actually uses them.

Computer Language
• Digital devices have two stable states, which
are referred to as zero and one by convention
• The binary number system has two digits, 0 and
1. A single digit (0 or 1) is called a bit, short for
binary digit. A byte is made up of 8 bits.
• Binary Language: Data and instructions
(numbers, characters, strings, etc.) are encoded
as binary numbers - a series of bits (one or
more bytes made up of zeros and ones)

Computer Language (cont.)
• Encoding and decoding of data into binary is
performed automatically by the system based
on the encoding scheme
• Encoding schemes
– Numeric Data: Encoded as binary numbers
– Non-Numeric Data: Encoded as binary numbers
using representative code
• ASCII – 1 byte per character
• Unicode – 2 bytes per character

Binary Number System
• Decimal
– Base 10, ten digits (0-9)
– The position (place) values are integral powers of 10:
100
(ones), 101
(tens), 102
(hundreds), 103
(thousands)…
– n decimal digits - 10n
unique values
• Binary
– Base 2, two digits (0-1)
– The position (place) values are integral powers of 2:
20
(1), 21
(2), 22
(4), 23
(8), 24
(16), 25
(32), 26
(64)…
– n binary digits - 2n
unique values

Programming Languages
• Computers can not use human languages, and
programming in the binary language of
computers is a very difficult, tedious process
• Therefore, most programs are written using a
programming language and are converted to
the binary language used by the computer
• Three major categories of prog languages:
– Machine Language
– Assembly Language
– High level Language

Machine Language
• Natural language of a particular computer
• Primitive instructions built into every
computer
• The instructions are in the form of binary code
• Any other types of languages must be
translated down to this level

Assembly Languages
• English-like Abbreviations used for operations
(Load R1, R8)
• Assembly languages were developed to make
programming easier
• The computer cannot understand assembly
language - a program called assembler is used
to convert assembly language programs into
machine code

High Level Languages
• English-like and easy to learn and program
• Common mathematical notation
– Total Cost = Price + Tax;
– area = 5 * 5 * 3.1415;
• Python, Java, C, C++, Javascript

Compiling Source Code
A program written in a high-level language is called a
source program (or source code). Since a computer cannot
understand a source program. Program called a compiler is
used to translate the source program into a machine
language program called an object program. The object
program is often then linked with other supporting library
code before the object can be executed on the machine.
16
Compiler
Source File Object File Linker Excutable File

Programming
 Programming – the creation of an ordered set of
instructions to solve a problem with a computer.
 Only about 100 instructions that the computer
understands - Different programs will just use
these instructions in different orders and
combinations.
 The most valuable part of learning to program is
learning how to think about arranging the
sequence of instructions to solve the problem or
carry out the task

Programming Fundamentals: Putting the
Instructions Together
• Sequential Processing
– A List of Instructions
• Conditional Execution
– Ifs
• Repetition
– Looping / Repeating
• Stepwise Refinement / Top-Down Design
– Breaking Things into Smaller Pieces
• Calling Methods / Functions / Procedures / Subroutines
– Calling a segment of code located elsewhere
– Reuse of previously coded code segment

Methods of Programming
• Procedural
– Defining set of steps to transform inputs into outputs
– Translating steps into code
– Constructed as a set of procedures
– Each procedure is a set of instructions
• Object-Oriented
– Defining/utilizing objects to represent real-world entities that
work together to solve problem
– Basic O-O Programming Components
• Class
• Object/Instance
• Properties
• Methods

Object Oriented Programming
• Class
– Specifies the definition of a particular kind of object
• Its Characteristics : Properties (or Attributes)
• Its Behaviors: Methods
– Used as blueprint / template to create objects of that type
• Object/Instance
– A specific instance of a class – an object created using the Class
Definition
– All specific instances of the same class share the same definition
• Same Properties – can be modified
• Same Methods – can be modified

Class and Object Example
Class (aLL DOGS)
• All Instances of Class Dog
Have
– Properties
• Name
• Breed
• Weight
• Color
– Methods
• Walk
• Bark
• Jump
Object (one dog)
• A particular Instance Could
Have
– Properties
• Name -Spot
• Breed - Mutt
• Weight - 10 pounds
• Color - Black
– Methods
• Walk
• Bark
• Jump
(these can also be modified to fit
a particular dog)

Problem Solving
 The process of defining a problem, searching for
relevant information and resources about the
problem, and of discovering, designing, and evaluating
the solutions for further opportunities. Includes:
 Finding an Answer to a Question
 Figuring out how to Perform a Task
 Figure out how to Make Things Work
 Not enough to know a particular programming
language… Must be able to problem solve…
 Very desirable to be a good Problem Solver in any CIS
discipline.

Polya’s 4 Steps of Problem Solving
• U – Understand the Problem
• D – Devise a Good Plan to Solve
• I – Implement the Plan
• E – Evaluate the Solution

Example:
Solving Math Word Problem
• Read the Problem: Understand the
description of problem or scenario, identifying
the knowns and unkowns
• Decide how to go about solving the problem:
Determine what steps need to be taken to
reach the solution
• Solve the Problem: Write the solution
• Test the Answer: Make sure the answer is
correct

Solving Computing Problems
• In general, when we solve a computing
problem we are taking some inputs,
processing (performing some actions on) the
inputs, and then outputting the solution or
results.
• This is the classic view of computer
programming – computation as calculation
• Polya’s steps (UDIE) can be very effective
when applied to solving computing problems

Applying Polya’s Problem Solving to Programming
Step 1 - Understand the Problem
• What is the Problem to be solved? What is the
unknown? What is the condition? What is the
data? What is needed to solve the problem?
What actions need to take place?
• Identify the inputs and outputs
• Identify the processes needed to produce the
outputs from the given inputs
• Draw a figure. Introduce suitable notation.
• Isolate Principle parts of the problem.

Step 2 - Devise a Plan
• Find connections between the knowns and
unknowns.
• Simplify: Break the problem into smaller sub-
problems
• Design a solution
• Make a plan or list of actions to implement
the solution
– Algorithm / Flowchart / Psuedocode

Step 2 - Devise a Plan (cont.)
• Algorithm
– A FINITE set of clear, executable steps that will eventually
terminate to produce the desired outcome
– Logical design used to solve problems – usually a list of
actions required to perform task
• Pseudocode
– Written like program code but more “English Like” and
doesn’t have to conform to language syntax
• Flowchart
– Diagram that visually represents the steps to be performed
to arrive at solution.

Step 3 - Implement the Plan
• Implement in a Programming Language
• Carry out the plan checking the preliminary
results at each step.
• Code A Little Test A lot

Step 4 - Evaluate the Solution
• Run the Code
• Check results repeatedly and thoroughly
– Use numerous test cases or data sets
– Use highly varied test case, including expected as
well as and unexpected cases
• Look for new solutions
– Is there a better, easier, or more efficient solution
• Can other problems be solved using these
techniques?

Summary
• U - Read the Problem Statement
– Identify the inputs, outputs, and processes
• D - Decide how to Solve the Problem
– Create an Algorithm / Flowchart / Psuedocode
• I - Program the Code
– Implement in Programming Language
• E - Test the Solution
– Run the Code using numerous, varied test cases

computer programming introduction ppt.ppt

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