Exam 1 Review

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Review forExam 1
2
Computer hardware
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Data Representation

• Computer uses a binary (base 2) system with two
  unique digits 0 and 1, called bits (short for
  binary digits)
• byte - 8 bits grouped together as a unit

• ASCII Provides different combinations of 0s and
  1s to represent 256 (28) individual characters

• Numbers
• Uppercase and lowercase letters
• Punctuation marks

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Editor and C compilers

• A compiler is a translation program
• convert a program written in a higher-level
  language (source code) into machine language
  (machine code)
• Source code is usually in text format that can be
  edited using a text editor

C source code (.cpp)
Compiler (g)
Machine code (executable)
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A First Program (convert feet to inches)
// Program height.cpp // Convert feet to
inches // Author(s) Im A. Programmer // Date
09/01/2004 include ltiostreamgt using namespace
std int main () int Feet, Inches
Feet 6 Inches Feet 12 cout ltlt
Height is " ltlt Inches ltlt "in. ltlt endl
return 0 // end main
For peoples benefit
Commentmarker
input output librarydefinition file
Compiler directive
main ( ) Function says where program starts
running
Variable declarations
Every statementends with a semicolon.
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The Basics

• Naming Rules
• Keywords
• Identifiers Variables
• Letters (upper and/or lower case) a, b, x, y,
• Digits 1, 2, 0,
• A name cannot start with a digit
• Underscores _
• A name should not start with an underscore
• Variable Declarations
• Simple int I int J, K
• Initialized float Length 0.0
• Constant const int NBR 256
• Console I/O
• Input cin gtgt I gtgt J gtgt K
• Output cout ltlt Your score is " ltlt score ltlt endl

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Data Types

• Numeric Data Types
• Integer int, short, long
• 45 -69745 22L
• Floating-point float, double, long double
• 0.0F -58.0 3.14159L 22.6E45 44.8E-9
• Character Data Type
• char
• 'a' ''
• '\n' '\''
• Compatible with numeric types (ASCII encoding)
• Boolean Data Type
• bool
• true, false
• Compatible with numeric types

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Numeric Operators

• Arithmetic
• , -, , /,
• Assignment
• Operators
• - /
• Process
• Calculate value of expression to right of
  assignment operator
• Store or include value into variable to left of
  operator, with type conversion if necessary
• Swapping two variables
• Temp Var1Var1 Var2 Var2 Temp

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More Numeric Operators

• Assignment Conversions
• From int to double extend with .0
• From double to int chop off fraction
• Integer Division
• Integer division produces integer result
• (Number (5 / 9)) is the same as (Number 0)
• Modulus Operator
• Gives the integer remainder of dividing the two
  integer operands
• 5 2 5 / 2 2 R 1 so (5 2) yields 1
• 12 4 12 / 4 3 R 0 so (12 4) yields 0

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Logical Expressions

• Relational Operators
• !
• lt lt gt gt
• Logical Operators
• !
• Precedence
• Highest parentheses
• Next arithmetic
• Next relational
• Next logical ( is higher than )
• Score1 80 Score2 75 Age 35
• if (Score1 gt 90 Score2 gt 85 Age gt 30)
• Lowest assignment

I gt 0 I lt 0
I gt 0 I lt 10) ! (I lt 0 I gt 10)
NO short-circuit here
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Basic if Groups

• One-Way
• if (Value lt 0)
• Value -Value
• Two-Way
• if (B ! 0)
• C A / B
• else
• C 0

false
if
true
true
false
if
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Multiple Selections if else if else

• if ((Grade 'A')
• (Grade 'B')
• (Grade 'C'))
• cout ltlt "Pass." ltlt endl
• else if (Grade 'D')
• cout ltlt Maybe." ltlt endl
• else if (Grade 'F')
• cout ltlt "Fail." ltlt endl
• else
• cout ltlt "Error!" ltlt endl

false
if
true
false
else if
true

false
else
true
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Multiple Selections

• switch
• switch (Grade)
• case 'A' case 'B' case 'C'
• cout ltlt "Pass." ltlt endl
• break
• case 'D'
• cout ltlt Maybe." ltlt endl break
• case 'F'
• cout ltlt Fail." ltlt endl break
• default
• cout ltlt "Error!" ltlt endl

• if else-if else
• if ((Grade 'A')
• (Grade 'B')
• (Grade 'C'))
• cout ltlt "Pass." ltlt endl
• else if (Grade 'D')
• cout ltlt Maybe." ltlt endl
• else if (Grade 'F')
• cout ltlt "Fail." ltlt endl
• else
• cout ltlt "Error!" ltlt endl

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Coding Style

• Comments
• At top of program, to document name, purpose,
  author, date written / modified, etc.
• Before blocks of code, to say what they do
• On declarations, to tell purpose of variable
  being declared
• Indentation
• All code within a block or control construct is
  indented
• If blocks are nested, then so is the indentation
• Braces
• use them around the body of main function
• use them around the body of a control construct

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Linux commands, g compiler, etc

• ls list files in working directory or other
  directories
• mkdir create a directory
• cd change working directory
• cp copy a file to another file
• mv rename a file or move it to another directory
• rm delete a file or files
• rmdir remove empty directory

• To compile g myfile.cpp
• To run ./a.out