software

software

1. translators

   • all code must be translated to machine code in order to run.

2. high level code is designed for humans to read and write

   • computers can not run high level code, in order to run code, it must be translated into machine code
   • using a compiler
     • a compiler takes the code and translates it all in one go, creating a new executable file at the end. the file contains only machine code, the original high level code is not included. This file can be executed directly by the computer.
     • advantages - speed, a compiler program will run much faster, as all the translation has already been done. Security, you can distribute the executable file without the source code, making it harder to reverse engineer.
   • using an interpreter
     • an interpreter does not create a new file. It is used to execute the source code directly. It translates and executes the high level code line by line.
     • advantages - compatibility, your code will run on any computer that has the interpreter available. a compiled executable can only run on the computer it was compiled for. debugging, easier to fix errors, as the interpreter can identify the line the error occurred on.

3. compilation stages

   • lexical analysis
     • comments and unneeded spaces are removed
   • symbol table construction
     • a symbol table is created to hold variable addresses, labels and subroutines
   • syntax analysis
   • semantic analysis
   • code generation
   • optimisation