Basic components of programming

Basic components of programming

1. Computer programs are written to process DATA

   • Data stored with different DATA STRUCTURES
     • COMPLEX
       • ARRAY/LIST
       • OBJECT
         • OOP
           • class
             • starts with class keyword, followed by class name and colon eg class LivingThings():
           • methods and attributes
           • properties
           • instance
           • encapsulation
     • SIMPLE
       • VARIABLE
         • global
           • at start
         • local
           • for specific function
         • $number = 0; $name = 'John Smith';
         • superglobals
           • always available regardless of scope
   • DATA TYPE

2. Algorithm CONTROL STRUCTURES

   • SEQUENCE
     • step by step
       • statement; statement; statement;
   • SELECTION
     • true/false
     • if-then-else
       • if (condition) { statement; statement; }
         • Statement executed only when TRUE
       • if (condition) { statement; statement; } else { statement; statement; }
       • if (condition) { statement; statement; } else if (condition) { statement; statement; } else { statement; statement
   • ITERATION
     • counted loop
       • for
         • for ($variable=0; $variable < somenumber; $variable++) { statement; statement; }
         • for (initialization expression; test condition; update expression) { // code to be executed }
     • pretested loop
       • while
         • while (condition) { statement; statement; }
         • while (set condition true){code;}
       • certain condition met at start of loop
     • post tested loop
       • used for looping until condition met at end of loop
       • do-while
     • foreach loop
       • used in arrays
   • CONDITION
     • logical expression
     • logical operators AND OR NOT

3. Arithmetic

   • Basic maths calculations + - * /

4. FUNCTIONALITY

   • METHODS
     • see OOP
   • FUNCTIONS
     • function function_name($somevariable){ executable code; }
     • to use (call) a function use just its name followed by semicolon eg displayName()
     • Consists of three parts: function name, set of () to hold incoming variables, set of {} to enclose code for function
   • Forms
     • <formaction = "where it goes file.php" method "post">
     • input element example: <input name="something" type ="input type" value "something">
       • input name used for $_POST variable
       • input value passed when submit button pressed
     • form element example: <form name="something" method ="post" action "someaction.php"></form>

5. Control Flow of program

   • Event listeners like mouse click
     • events trigger functions to run

6. naming conventions

   • variables
     • starts with $, lowercase (snake case) with underscore between words
   • function
     • lowercase with underscore between words
     • do things so name must use verb
     • include keyword function as part of the name
       • name must reflect what function does
   • inside a class
     • properties (variable inside a class or object
       • camelCase (starts with lowercase
     • methods (similar to function but in class or object)
       • same as properties
   • constants
     • UPPERCASE with underscore between
   • classes
     • Titlecase (starts with uppercase), singular
   • files
     • lowercase with underscore
   • class files
     • match class name

7. common issues

   • indentation must be correct - use three spaces not tab
   • lines with conditionals (if,else etc) must be terminated with semi-colons
   • capitals are important
   • parentheses and braces must match closing ones
   • quotes around strings