PROGRAM ESSENTIALS

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PROGRAM ESSENTIALS
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TOKENS

• SMALLEST UNITS OF A PROGRAM LANGUAGE
• Special Symbols
• Mathematical Operators
• Punctuation
• Word Symbols
• Key Words or Reserved Words
• Identifiers / Operations(functions)
• Predefined Operations(functions)
• Can Be Redefined By Programmer (Will Get You Into
  Trouble)
• User Defined Identifiers / Operations(functions)
• Non-Reserved Word
• First Character Must Be Alpha
• No Embedded Blanks
• No Special Characters (,-,,/.) (Only
  Underscore Is Allowed)

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DATA TYPES

• SIMPLE DATA TYPES
• Integral (ordered data types)
• Whole Numbers (int)
• Characters (char)
• Boolean (bool)
• Floating-Point (real numbers)
• Float (-3.4E38 to 3.4E38)
• Double (-1.7E308 to 1.7E308)
• String (Must Include String Library)
• Sequence of zero or more characters
• Strings are enclosed in double quote marks(Mark)

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OPERATORS

• ARITHMETIC OPERATOR
• (Addition)
• - (Subtraction)
• (Multiplication)
• / (Division)
• (Modulus) (Can Only Be Used With Integrals)
• EVALUATION RULES
• Evaluates To An Integer With Integer Operands
• Evaluates To Floating-Point(FP) With FP Operands
• Evaluates To FP With Mixed Operands
• Modulus Always Evaluates To Integer

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OPERATORS

• HIERARCHY
• ( ) PRIORITY 1
• , / , PRIORITY 2
• , - PRIORITY 3
• EVALUATION
• Parentheses (From Inside Out)
• All Others (From Left To Right)

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CONSTANTS

• DECLARED PRIOR TO MAIN
• const (datatype) (identifier) (value)
• VALUE IS SET WHEN PROGRAM RUNS
• CANNOT CHANGE WHILE RUNNING
• Examples
• const double RATE 0.065
• const int MIN_ORDER 20
• const char BLANK

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VARIABLES

• MUST BE DECLARED BEFORE USED(at top of function)
• IDENTIFIES NAME TO MEMORY LOCATION
• IDENTIFIES NAME TO TYPE
• CAN BE INITIALIZED AT DECLARATION
• int main( )
• int age
• char sex
• float rate 0.065 //Initialized

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ASSIGNMENT / INPUT / OUTPUT

• Assignment uses operator
• Only One Token Left Of Operator Allowed
• test 0.0
• count count value
• x y z
• Input uses cin (cin gtgt variable gtgt . )
• cin gtgt hours
• cin gtgt hours gtgt payrate
• Data Must Be Separated By One Space Or Tab

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ASSIGNMENT / INPUT / OUTPUT

• Output uses cout (cout ltlt variable ltlt )
• cout ltlt Enter The Pay Rate.\n
• cout ltlt gross_pay ltlt endl

Escape Name ASCII Comments
\a Bell 7 Sounds an audible alarm (rings the bell) at the console.
\b Backspace 8 Moves the cursor one space to the left
\t Tab 9 Inserts a tab at the current cursor position
\n Linefeed 10 Moves the cursor to the next line
\r Return 13 Moves the cursor to the beginning of the same line
\ Double Quote 34 Inserts a double quote at the cursor position
\ Quote 39 Inserts a single quote at the cursor position
\\ Backslash 92 Inserts a back slash at the current cursor
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OUTPUT FORMATTING

• Numeric Manipulators
• Must Include ltiomanipgt
• fixed or scientific Sets Fixed Decimal Format
  or Scientific Format
• showpoint or noshowpoint Ensures Decimal Point
  Is Displayed or Not
• setprecision Sets Number of Decimal Places
• Works On All Floating Point Numbers After It Is
  Invoked Or Until A Subsequent Statement Changes
  The Precision
• setw Sets Number Of Characters To Display
• Only Works On First Expression After It Is
  Invoked
• Must Invoke For Each Expression To Be Output
• right or left Sets justification (right is
  default)
• Remains in effect until changed to opposite
  justification
• setfill Sets the fill character used (default
  a space)

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INCREMENT / DECREMENT

• Types
• X (Post Increment) X- - (Post Decrement)
• X (Pre Increment) - - X (Pre Decrement)
• Both Produce The Result X X 1 or X X - 1
• Post Increments After Expression Is Evaluated
• Y X Z Is The Same AS
• Y X Z
• X X 1
• Pre Increments Before Expression Is Evaluated
• Y X Z
• X X 1
• Y X Z
• Decrement Works The Exact Same Way

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PROGRAM STRUCTURE

• COMPLETE PROGRAM
• include ltiostreamgt //Preprocessor Directive
• using namespace std //An ISO C Compiler
  Declaration
• const float PI 3.14159 //A Global Constant
• int main( )
• cout ltlt fixed ltlt showpoint ltlt setprecision(2)
  // Floating Point Setup
• cout ltlt Hello World! ltlt endl
  //Displays Hello World
• cout ltlt Pi ltlt PI ltlt endl //
  Displays Value Of PI
• cout ltlt endl //Cursor Moved Down One
• system (pause)
  //Stops window closing
• return 0

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COMMENTS

• COMMENTS
• Use / ../ Multi-line Comments
• Use // Single Line Comments
• Used To Explain Major Code Processes And Unique
  Program Solutions
• Good Comments Provide Much Needed Help When
  Debugging or Altering Existing Code (which just
  might be you)

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TYPE CONVERSION

• CONVERT ONE DATA TYPE TO ANOTHER
• Use Cast Operator
• static_cast ltdata type namegt expression
• static_castltintgt(7.9) Evaluates To 7
• static_castltdoublegt(25) Evaluates To 25.0
• static_castltintgt(A) Evaluates To 65
• static_castltchargt(65) Evaluates To A
• Using Cast Operator To Convert FP Values
  Truncates Decimal portion

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STATEMENTS

• PROGRAMS ARE BUILT OF STATEMENTS
• OUTPUT STATEMENT
• Used To Display Or Store Data
• INPUT STATEMENT
• Used To Accept Or Retrieve Data
• ASSIGNMENT STATEMENT
• Used To Store Data To Memory
• CONTROL STATEMENT
• Use To Control The Program Flow
• SELECTION (Making Choices)
• ITERATION (Repeating Processes)

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DEBUGGING

• Debugging Your Code
• A "bug" is a mistake in a program. So debugging
  is the process of eliminating errors in programs.
  
• Three types of program errors
• Compile-Time Errors
• Run-Time Errors
• Logical Errors

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DEBUGGING

• Compile Time Errors
• Occurs when you try to compile your code
• If Compiler is not able to compile the code it
  issues an error
• Compile-time errors listed under the compiler tab
• Compiler finds most of the problems with syntax
• Examples
• Missing semi-colon
• Undeclared variable
• Error message does not always show correct
  location of error
• Error will always be at or above the line the
  message refers to
• If errors exist an executable file is not
  created.

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DEBUGGING

• Runtime Errors
• Run time errors occur during program execution
• The program terminates abnormally (crash or
  hang).
• Examples
• Trying to divide by zero
• Trying to access memory you are not allowed to
  access
• Can be difficult to find
• Typically requires the use of debugger to find
  error

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DEBUGGING

• Logical Errors
• Program runs but does not produce correct results
• Examples
• Missing or brace caused faulty logic
• Misunderstanding of the formulas used by the code
• Overall program flow
• These are often the most difficult to diagnose
• May require use of debugger to find error

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IN THE END

• The Programmers Job Is To
• Design the program
• Write the code
• Debug the code to eliminate all errors
• Test the code to validate the output