Programming Language Translators

• What do computers execute?

  Machine code
• Why is machine code difficult for humans?

  It is hard to read, write, and debug
• What might a machine code instruction look like?

  01000101
• How do assembly code instructions compare to machine code?

  They are easier for humans to work with
• What type of language is assembly code?

  Low level language
• What does an assembler do?

  Translates assembly code into machine code
• Why is object code hardware specific?

  Each processor has its own instruction set
• What does a compiler do?

  Translates high-level language into machine code
• What is the resulting machine code from a compiler called?

  Object code
• How is object code produced?

  It is hardware specific
• What does an interpreter do?

  Translates high-level language into machine code
• How does an interpreter execute code?

  Line by line
• What are the differences between a compiler and an interpreter?

  • Compiler:
  • Runs programs multiple times without recompilation
  • Faster execution
  • Executable code does not need interpreter
  • Compiled code is hard to read

  
  

  • Interpreter:
  • Source code runs on any machine with interpreter
  • Small errors don't require recompilation
• What is bytecode in programming?

  Intermediate step between source and machine code
• How is Java related to bytecode?

  Java is compiled into bytecode
• What interprets bytecode?

  Bytecode interpreter
• What are the stages of compilation?

  1. Lexical analysis
  2. Symbol table
  3. Syntax analysis
  4. Semantic analysis
  5. Code generation
• What happens during lexical analysis?

  Unnecessary spaces and comments are removed
• What are tokens in lexical analysis?

  Represent functions in the program
• What might tokens look like for the code "age = 17; print(age);"?

  <identifier> <operator> <number> <keyword> <open_bracket> <identifier> <close_bracket>
• What does the symbol table do?

  Keeps track of memory addresses for identifiers
• What occurs during syntax analysis?

  Tokens are checked against language rules
• What happens if a phrase is not valid in syntax analysis?

  An error will be recorded
• What is a syntax diagram?

  Visual representation of syntax rules
• What does semantic analysis check for?

  Valid syntax that is not a valid program
• What occurs during code generation?

  Machine code is generated from the program
• What is code optimization?

  Improving code efficiency and removing redundancies
• What are libraries in programming?

  • Sets of pre-written functions
  • Examples: random number generation, math operations
  • Programmers can write their own libraries
  • Library functions can be called in programs
• What does a linker do?

  Links memory addresses for library functions
• What is the role of a loader?

  Copies program into main memory to run
• Why does the loader relocate memory addresses?

  Some memory may already be in use