python

python

1. what is it

   • interpreted, general purpose, high level programming language
   • created by Guido van Rossum in 1991
   • sequencing must be in order for the code to work
     • when sequencing is in the right order, it is called an algorithm
       • algorithms are the different steps involved to undertake the process of solving a problem
     • if there is a problem, decomposition must take place to break it down into different steps
     • a sequence is the order in which the computer must follow to perform the right task
   • the code which constructs and instructs the computer
   • development environment
     • app is called IDLE
     • there are 2 modes

2. syntax errors

   • this is where bugs come from - the wrong code messes up the computer
   • when the code has an error in the script

3. variable names

   • a variable is a place or location which temporarily stores information
   • they can be any length and can consist of uppercase and lowercase letters ( A-Z , a-z ), digits ( 0-9 ), and the underscore character ( _ ). An additional restriction is that, although a variable name can contain digits, the first character of a variable name cannot be a digit.
   • strings / stringlines
     • they represent uncoded characters
     • needs inverted commas or quote marks to work
     • you can assign a variable to a string using the equal sign, eg: a = "Hello" / print (a)
     • for multiline strings (a string with more than one word included), surround the strings with 3 quotation mark / inverted commas
     • strings are arrays - each character inside the quote marks is just one string (referred to as an index), coming together to make a big string. you can break up these strings as they are numbered, the first being 0, then 1, 2, etc. to break them up, use squared brackets around the string you want to show inside the print brackets.
       • you can also use the slice syntax to enclose a group of strings you want to show. specify the start and end index, separated by a colon, inside squared brackets, inside the print brackets.
         • one more thing you can do is negative indexing - simply add a minus symbol before each number and the only code registered will be: for the first number - that number of strings from the end. for the second number - that number of strings from the first

4. comments

   • they are for developers. They describe parts of the code where necessary to facilitate the understanding of programmers, including yourself. To write a comment in Python, simply put the hash mark # before your desired comment: # This is a comment.

5. functions

   • a function is a special built-in routine that does a specific job
   • they appear in purple
   • print() and input() are examples

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