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CSC 2400: Computer Systems

CSC 2400: Computer Systems. Week 1 – C versus Java. Reminders. Sign up for ZyBook – VILLANOVACSC2400RobsonFall2019 HW 1 – Due a week from today http://www.csc.villanova.edu/~mprobson/courses/csc2400/hw1.html Sign up for Piazza (23/42) - https://piazza.com/villanova/fall2019/csc2400.

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CSC 2400: Computer Systems

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  1. CSC 2400: Computer Systems Week 1 – C versus Java

  2. Reminders • Sign up for ZyBook – VILLANOVACSC2400RobsonFall2019 • HW 1 – Due a week from todayhttp://www.csc.villanova.edu/~mprobson/courses/csc2400/hw1.html • Sign up for Piazza (23/42) - https://piazza.com/villanova/fall2019/csc2400

  3. CSC 2400-001 Survey Statistics • Familiar with Unix • 1yes, 18 no • Familiar with C • 2yes, 17 no (barely) • Familiar with C++ • 3 yes (sorta), 16 no (barely) • Compute the sum of all integers from 1 to 100 • 18 yes, 1 no • Binary to decimal • 7yes, 12 no

  4. CSC 2400-002 Survey Statistics • Familiar with Unix • 2yes, 21 no • Familiar with C • 2 yes (somewhat), 21 no • Familiar with C++ • 8 yes (mix), 15 no • Compute the sum of all integers from 1 to 100 • 20 yes, 3 no (maybe) • Binary to decimal • 7 yes (maybe), 16 no (IDK, probably not)

  5. Hierarchy of Computer Languages Source: https://thebittheories.com/levels-of-programming-languages-b6a38a68c0f2

  6. C vs. Java: Design Goals • Java design goals • Support object-oriented programming • Allow same program to be executed on multiple operating systems • Support using computer networks • Execute code from remote sources securely • Adopt the good parts of other languages (esp. C and C++) • Implications for Java • Good for application-level programming • High-level • Virtual machine insulates programmer from underlying assembly language, machine language, hardware • Portability over efficiency • Security over efficiency • Security over flexibility

  7. C vs. Java: Design Goals • C design goals • Support structured programming • Support development of the Unix OS and Unix tools • As Unix became popular, so did C • Implications for C • Good for system-level programming • But often used for application-level programming – sometimes inappropriately • Low-level • Close to assembly language; close to machine language; close to hardware • Efficiency over portability • Efficiency over security • Flexibility over security

  8. C vs. Java: Design Goals • Differences in design goals explain many differences between the languages • C’s design goal explains many of its eccentricities • We’ll see examples throughout the course

  9. C vs. Java: Overview (cont.) • Bad things you can do in C that you can’t do in Java • Shoot yourself in the foot (safety) • Shoot others in the foot (security) • Ignore wounds (error handling) • Dangerous things you must do in C that you don’t in Java • Explicitly manage memory via malloc() and free() • Good things you can do in C, but (more or less) must do in Java • Program using the objected-oriented style • Good things that you can’t do in C but can do in Java • Write completely portable code

  10. C vs. Java

  11. C vs. Java (cont.)

  12. C vs. Java (cont.)

  13. C vs. Java Example

  14. C vs. Java (cont.)

  15. C vs. Java Example

  16. C vs. Java (cont.)

  17. Source: https://www.xkcd.com/292/

  18. C vs. Java Example

  19. C vs. Java (cont.)

  20. C vs. Java Example

  21. C vs. Java (cont.)

  22. C vs. Java Features • Java • Object-oriented • Portable • Secure • C • Efficient • Flexible • Lower level (closer to the system)

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