Computers and Programming Languages

• What is a Computer?

  • computes
  • electricity
  • on/off = binary
  • encoding

• How do we tell a computer what to do?

  • instructions
  • add
  • subtract
  • multiply
  • read
  • write
  • computers take their instructions in binary, and do exactly as they're told.
  • humans don't think in binary very well
  • assembly
  • example hello, world assembly
  • humans don't think in assembly very well either

• higher-level languages

  • English is bad
  • Grace Hopper: lather, rinse, repeat
  • precise english (lawyers)
  • FORTRAN, COBOL, PASCAL
  • C and its descendants
  • C++
  • Java
  • C#
  • BASIC
  • qbasic
  • vb
  • lisp
  • perl
  • ruby, python

• compilers

  • grace hopper invented: She did this, she said, because she was lazy and hoped that "the programmer may return to being a mathematician."
  • take high-level and compile into assembly, then convert assembly into binary

• How the computer sees the world

  • electrical signals
  • logic gates
  • peripherals
  • input/output
  • RAM and hard disks
  • Memory Model

• Why C?

  • C is the lingua franca
  • C is powerful and simple
  • C gives you unfettered access to the computer
  • To understand C is to understand the computer

• Why not C?

  • strings
  • security
  • productivity is better with other languages
  • software engineering (OOP, etc.)

• Overview of C

  • sequential
  • procedural (functions)
  • variables
  • libraries