CIS 103 - Computer Programming Logic

1
CIS 103 - Computer Programming Logic

• Programming Concepts
• Overview
• prepared by Jack Wilson
• Cerritos College

2
Topics

• 1.1 Programs
• 1.2 Modules1.3 Algorithms1.4 Statements1.5 Synt
  ax Semantics1.6 Logic Planning Tools
  1.7 Control Structures 1.8 Memory Concepts
• 1.9 Data Types

3
1.1 Programs

• A program contains one or more modules.
• Some languages require a module with a special
  name, such as "main" for a program to be
  created.
• Programs are often also referred to as
  applications or more generally as software.

Program
module
module
4
1.2 Modules

• A module is a collection of statements that
  performs a specific task within a program.
• Module is a generic term. Programming languages
  uses different names for modules. Examples
  include
• function C, C, VisualBasic
• method Java
• subprocedure VisualBasic

5
1.3 Algorithms

• An algorithm is the name given to the logic that
  is developed and used to code the statements in a
  module.

Implementation of the algorithm in a module
(function) double square ( double number )
return number number

• Algorithm to square a number
• get a number
• multiply the number by itself
• return this value

6
1.4 Statements

• A statement is the name given to a high level
  language instruction.
• Programs are written using a variety of different
  types of statements. Examples include
• Input
• Output
• Declaration
• Assignment
• Processing
• Compiler / Pre-Processor Directives

7
1.5 Syntax Semantics

• Syntax refers to the rules of a language that
  must be followed to construct a valid statement.
  Statements are constructed using the following
  components
• reserved words ( aka keywords )
• identifiers
• operators
• literals
• punctuation symbols
• Semantics refers to the meaning of a statement.
  It addresses the question "What does the
  statement do?.

8
1.6 Control Structures

• A control Structure determines the flow of
  execution for statements executing in a module.
• There are 3 control structures that are used in
  all programming languages
• Sequence
• Selection
• Repetition

9
1.6 Control Structures
Sequence Structure A single statement
or multiple statements executed
sequentially, one after another.
Example 2
Example 1
10
1.6 Control Structures
true
false
Selection Structure Asks a question and based on
the answer ( true or false ) one of possibly 2
paths of execution is taken.
Example 1 One path of execution
true
false
Example 2 Two paths of execution
11
1.6 Control Structures
Repetition Structure Asks a question and based
on the answer ( true or false ) executes a
statement. Continues to execute the statement
as long as the question evaluates to yes. A
repetition structure is usually called a "loop".
true
false
Example 1 Pre-test loop
true
false
Example 2 Post-test loop
12
1.7 Logic Planning Tools

• Pseudocode
• Flowchart
• IPO ( Input - Process Output ) Chart
• Structure Chart
• Decision Tree/Table
• Printer Spacing Chart
• Screen Layout Chart
• Record Layout Form text file
• Table Definition database file

13
1.8 Memory Concepts

• Memory is measured in bytes ( MB / GB / TB )
• A byte is 8 bits ( binary digits )
• Every byte is assigned a unique address in
  memory
• Data types use one or more bytes to store
  information
• There are different formats for storing different
  types of data. Characters are stored quite
  differently than are real numbers or dates.

14
1.8 Memory Concepts

• To avoid having to reference a specific location
  in memory to access a piece of data, variable
  names are used instead of addresses. To use a
  variable in a program, you must declare the
  variable by giving it a name and a data
  type.Examples
• int count boolean finished Dim name As
  String
• When a program is executed, a symbol table (
  think of it as a data dictionary in memory ) is
  created that maps the name of a variable to the
  location in memory where the data is being
  stored.

15
1.9 Data Types
Programs work with data ( information stored in
locations in memory ).There are many different
categories of data.

• Numeric
• integer numbers
• real numbers
• Text
• a single character value
• a "string" of characters
• Boolean
• True
• False
• Currency
• Date/Time
• Object

Every language has a specific keywords which are
used to specify a data type. Not all data types
are supported in all languages. Here are some
examples
Language Numeric Text Boolean Currency
Java int long float double char String boolean not supported
C int long float double char char string bool not supported
VisualBasic Integer Long Single Double Char String Boolean Decimal