Programming Environments

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Programming Environments
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Outline

• Error types
• Language Types
• Translation Approaches

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Types of Errors

• Syntax Error
• Incorrect use of languages defined set of key
  terms and operators
• Compiler or interpreter usually catches
• Run-time Error
• Found when running
• Logic Errors
• Compiler typically doesnt catch

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Programming Language Types

• Procedural
• Object-Oriented
• Markup
• Scripting
• Event-Driven

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Procedural Languages

• Have Starting and Ending Points
• Series of instructions essentially executed in a
  linear fashion
• E.g., Pascal, C

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Object-Oriented

• Objects support inheritance
• Reduces development costs
• Object listen to and respond to messages
• Objects Have
• Attributes fields
• Methods Operations

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Markup Languages

• Formatting rules associated with specific code.
• E.g., HTML

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Scripting Languages

• Instructions recorded in scripts
• Scripts require a host application that
  interprets and executes each line a script during
  execution
• E.g., Java Script

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Event-Driven

• Attach code to Objects
• Application is triggered by events

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The Need to Translate

• We write in high-level languages
• Programming Source Code
• Scripting language
• Machines run Low-level language
• Requires translation
• Traditional Compilers are specific to CPU type
  (architecture)

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Classic Compilation

• Compiler translates source code to machine-level
  object code.
• Translate once, run many
• Outcome machine language instructions in the
  form of .EXE and .dlls
• Fast because machine runs machine code and
  doesnt have to translate at run time.

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Interpreted

• Interpreter converts code to machine language
  line-by-line just before execution.
• Translate every time
• Slower because it must translate for every use

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Translation Methods
2-Level
High-level
Compiler
Classic Compiled
Interpreted
Intermediatelevel
JVM or CLR
Machine level
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Translation Methods
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Java 2-Level Approach
Inter-mediatelevel
Java Code
bytecode
Compiler
High-level
Mac JVM
PC JVM
JVMs are in the computers browser
Machine code
Machine code
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Creation and Use of Java Applets
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Comparison of Java and Java Script
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Evaluation of Scripts and Applets

• Client Application Web Browser with interpreter
  or JVM
• Advantages
• Easy updates on server
• Scripts and Applets distributed from server to
  client at run-time
• Platform independence
• Disadvantages
• Slower performance, Internet bandwidth constrains
  performance, applets not permitted through some
  firewalls