Module 1

Module 1

1. 1. How does a computer program work?

   •    The computers can only execute extremely simple operations, they can evaluate the results of very fundamental operations but they can do it very fast and can repeat these actions virtually any number of times. So, they need instructions how to do that actions, these instructions are passed through programming languages.   
   • The computer can only execute extremely simple operations
     • But they can evaluate operations very fast
       • But they need instrutions to do that
         • A programing language is a way to pass instructions to the computer works

2. 2. Languages

   • Programing Languages
     • Machine Language
       • Very rudimentary where the commands it recognizes are very simple.
         • IL - The commands that the computer know is called instruction list (IL).
     • High Level Languages
       • They are more similar to natural languages
       • More complex than machine language
       • More simple than natural languge
       • Source Code
         • A program written in a high-level programming language .
       • Source File
         • The file containing the source code
   • Natural Languages
     • Language is means and a tool for expressing and recording thoughts.
       • Composition for a language
         • Alphabet
           • A set of symbols used to build words of a certain language.
         • Lexis
           • (aka dictionary) a set of words that exists in this language.
         • Syntax
           • A set of rules used to determine if a certain string of words form a valid sentence (e.g., "I am a python" is a syntactically correct phrase, while "I a python am" isn't)
         • Semantics
           • a set of rules determining if a certain phrase makes sense (the meaning, e.g., "I ate a doughnut" makes sense, but "A doughnut ate me" doesn't)

3. 3. Translation of the language to the computer

   • Compilation
     • Which is.
       • The source file is translated once by generating a file containing the machine code.
     • Compiler
       • The program tht perform that translation is the compiler.
   • Interpretation
     • Which is.
       • The source program is translating each time it has to be run.
     • Interpreter
       • The program that performing this kind of transformation
     • How the interpreter works
       • 1. The interpreter reads the source file, from top to bottom and from left to right
         • 2. Finds an error in the line?
           • Yes
             • 3. it finishes immediately resulting in an error message
           • No
             • 3. The interpreter tries to execute
               • Read the line again

4. 4. Python

   • Python Versions
     • Python2 vs Python3
       • Python 2 scripts won't run in a Python 3 environment and vice versa.
   • Python aka CPython
     • Originaly Python was write in "C", all Pythons from PSF too.
   • Cython
     • A code write in Python and translate to C
       • Faster than Python already this is a problem in Python.
   • Jython
     • Is a version of Python writing in Java, that can communicate with Java infrastructure more effectively.
   • PyPy and Rpython