Topics Covered on Wednesday, 2010-07-28

• Judging Effectiveness of Programs
  • Accuracy (correctness)
  • Ease of use (User Interface)
  • Execution time (Efficiency)
  • Hardware resource usage
  • Maintainability
• Code Optimisation
  • Optimise for speed (typically)
  • Optimise for memory (less common)
• Code optimisation
  • Manual optimisation
  • Compiler optimisation
• Interpreters
  • Execute program line by line instead of generating a stand-alone executable program
• Interpreters vs Compilers
  • Speed of execution
    • Compiled programs faster than interpreted programs
  • Speed of development and debugging
    • Easier to test, debug and re-run in an interpreter
  • Run-time requirements
    • Interpreter needed at run-time, compiler not needed
  • Program portability
    • Better with interpreter
• Special Interpreters -- Java
  • Compiler compiles Java program into byte code
  • Byte-code is language of a virtual machine
  • Java interpreter executes byte-code on real machine
  • Very portable, faster than interpreter
  • Java Virtual Machines available for all platforms