Intro to Server-Side Programming

Week Two

PHP As A Language

• PHP can be treated as a distinct language with it’s own rules

• It has it’s own vocabulary - words that are familiar to the language

• PHP has distinct grammatical rules

• Syntax - rules to determine the composition of sentences

• Semantics - the meaning and significance of words

• Structure - the relationship between words

Grammar and Vocaublary

• Reserved Words and Keywords: if, else, ifelse; for, foreach, while, do; and, or, xor; public, private, protected

• Expressions: semicolon (;), curly braces ({...})

• Arithmetic: addition (+), subtraction (-), multiplication(*)

• Comparisons: equality (==), inequalities (!=), ranges (<=)

• Special cases: dollar($), braces ([...]), operators (&, |, <<)

• User & Built-in Constants: PHP_VERSION, E_ERROR, E_WARNING, E_NOTICE, MY_CONSTANT

• User & Built-in Functions: shuffle(), printf(), strlen()

The PHP Manual - http://php.net/manual/en/• In your “assignments” workspace, create a file called “assignment-2.1.md” to work on your

answers to the following questions:

• Find at least three different methods to get a random value from an array with a built-in function (Look in Array Functions)

• What does the built-in md5() function do? What is the default return value? What built-in functions work similarly?

• What is another name for “anonymous functions” in PHP and where are they in the manual? When were they added and what was the last feature added?

• What is the default value of the “memory_limit” setting in PHP? What value would I set to it in order to allocate ALL memory to PHP? How could I set that value and where would I find that in the manual?

Data Types - Literals

• Literals are also known as Primitive Values

• Representative of fixed values, such as numbers or text

• Four scalar types: boolean, integer, float (double) & string

• Two compound types: array & object

• Three special types: resource, NULL & callable

• What makes 1 different from 1.0?

Working With Variables

• Variables are storage locations with identifiers that contain values

• Variables are places to store your literals. Think of a bucket.

$a_variable // This is a bucket to hold literals!

$a_variable = “some value” // Now the bucket has stuff in it

$a_variable = “something else” // The bucket remains, but a new string is put in it

• Variables in PHP are always preceded with a dollar sign ($)

• Variables are not very useful empty, so they are usually followed with an assignment operator

Assignment Operators

• An operator accepts one or more literals or variables, performs an operation on them and returns the results, like a calculator.

$total = 1 // total is defined as 1

$total = $total + 1 // total is now 2

$total += 2 // total is now 4 (old total plus 2)

• Orders of operation and precedence still apply here!

Basic “Phrases”

• Variables, basic expressions and comments:

$david = ‘awesome’; // not entirely true

• Basic assignment and arithmetic operators:

$counter = 1; $counter = 2;

$counter = 1 + 1;

$counter += 2;

• Getting feedback from PHP:

echo $counter;

var_dump($counter); var_export($counter);

Assignment Two

Pulling Files From Git (cont)

• Open the project that you forked earlier or fork one now

• Grab around 50 lines of PHP from that project that show examples of literals, variables, function calls and other colored (important) things

• If there is something that you don’t recognize, note it for later

• The goal is to practice “reading” PHP grammar for now