Valencia College Introduction to Server-Side Development DIG1108C Lesson 6 - Fall 2014

1. Intro To Server Side Development
Week Six

2. General Review
• Literals:
• boolean
• integer
• float
• string
• array
• Variables:
• $anything
• $any['array']
• Expressions
• 1 + 1 == 2
• $a = $b + 1
• Control Structures
• conditional branches
• conditional loops:
• while, do-while
• for, foreach
• Workflow Diagrams:
• diamonds: decisions
• rectangles: process
• arrows: branches
• Version Control & Git

3. Review - Arrays
• An array type is a data type that is meant to describe a collection of values
or variables, each selected by one or more indices(keys) tha can be
computed at run-time of the program.
• By default, the array type in PHP generates computed, numerical indices,
starting with zero, to make a list:
var_dump(array( 'one', 'two', 3, 4, 4.1, 4.2 ));
$list = array(); $list[] = 'one'; $list[] = 'two';
• The value for the key can also be specified as any scalar literal (neither
array, object nor resource), often a string
var_dump(array( 'one' => 1, 2 => 'two' )):
$list[4] = 'four'; $list['five dot one'] = 5.1;

4. Control Flow Statements
• Control Flow - refers to the order in which the individual statements,
instructions or function calls of an imperative or declarative program are
executed or evaluated. Execution results in a choice being made as to
which of two or more paths should be followed.
• Types of Control Flow statements:
• continuation at a different statement (unconditional branch or jump)
• execute statements only if some condition is met (conditional branch)
• execute statements until some conditional is met(loop, conditional branch)
• execute defined statements and return (sub/co-routines, continuations)s
• stop executing statements (unconditional halt)

5. Review - Loops
• A loop is a sequence of statements which is specified once but which may be carried out several times in
succession, a specified number of times or indefinitely
• Specific number of times:
for ( $count = 0; $count < $max; $count++ ) do_something();
• Once per each item in a collection(array):
foreach ( $collection as $item ) do_something();
foreach ($collection as $key => $value ) do_something();
• Until some condition is met:
while ( $condition == true ) do_something();
do something(); while ( $condition );
• Indefinitely(infinitely):
while ( true ) do_something();
do something(); while ( true);

6. Procedural Programming
• Procedural programming is based on specifying the
steps the program must take to reach the desired state.
• Procedures, also known as routines, subroutines,
methods or functions contain a series of computational
steps to be carried out. Any given procedure might be
called at any point during a program's execution.

7. Declarations
• Unlike variables, functions must be "declared" to use
do_something(); // "calling" an undefined function
!! Fatal Error: function do_something is not defined
• The keyword function declares a function
function do_nothing() { }
do_nothing(); // "invoking" a function
• Each function can only be declared once:
foreach ( range(1, 10) as $loop )
function once_and_only_once() { }
!! Fatal Error: Cannot redeclare once_and_only_once()

8. Modular Programming
• Modular Programming ("top-down design" or "stepwise refinement") is a software
design technique that emphasizes separating the functionality of a program into
independent, interchangeable modules, such that each contains everything necessary
to execute only one aspect of the desired functionality
• Separation of Concerns - one piece at a time. Increasing the complexity of
a system compounds the difficulty of maintaining it; smaller and simpler
components are easier to maintain
• Abstraction - write it once and only once
• Encapsulation - everything needed is there
• Scoping - doesn't affect other elements

9. Functions
• Functions must start with the function keyword, must contain a valid
function identifier (with variables), provide an optional list of arguments
surrounded by parentheses, even if there are none, and a block of code:
function do_something( $an_argument, $another ) {
// Code goes here
}
• Nothing from outside is visible to code in the block
• Nothing inside the block is visible outside the function
• Pass values into a function as arguments at invocation:
do_something( 'some value', "$another_value );

10. $outside_of_scope = 'outside only';
function do_something( $an_arg, $arg_two = false ) {
$inside_of_scope = 'inside only';
if( $arg_two ) echo $outside_of_scope;
echo $an_arg; // passed in at invocation
return $inside_of_scope; // passed back out
}
do_something( 'now' ); // prints "now"
echo $inside_of_scope; // Notice: Undefined variable
do_something( 'again', true ); // Notice: Undefined variable

11. Assignment 6.1
Finding Functions

12. Finding Functions
• Pair up, login to Github
• Open an existing Workspace and find some functions
together
• Copy and paste the function definition for each into a new file
called assignment-6.1.md
• Identify the name of the function and the names of all of the
arguments with comments; bonus points for identifying the
return value of the function
• Find at least three invocations of each function

13. Assignment 6.2
Identifying Functions & Scope

14. Functions & Scope
• Find at least three functions in the WordPress project
• Document them in a new file called assignment-6.2.md
• Use the format: path/to/file.php:9999
• Identify the name of the function and its arguments with comments
• Identify the in-scope variables by name
• Identify the return value of each function
• Add and commit your file, push to Github