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;
Friday, October 4, 13
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)
Friday, October 4, 13
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);
Friday, October 4, 13
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.
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)
Friday, October 4, 13
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()
Friday, October 4, 13
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
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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 );
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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
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12. Finding Functions
Pair up, login to Github, login to Cloud9
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 in your assignments
workspace
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
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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
Friday, October 4, 13
![General Review
Reference: php.net
Literals:
boolean
integer
float
string
array
object
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
Cloud9 IDE:
cloning from Github
sharing workspaces
Friday, October 4, 13](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)