Beginning PHPSession #2

November 17, 2010

Josh Butts

Agenda for Today

•Go over Homework #1

•Include & Require

•Errors & Warnings

•String Functions

•Writing Your Own Functions

Corrections

•Use “echo $foo”, not “echo($foo)”

•I think we forgot to talk about code comments, so lets do that now

Comments

A note on constructs vs.

functions•A language construct is a core part of the language, like “true”, “include” and “isset”

•Some things in PHP behave like functions, but are actually language constructs

String Functions

•You’ll use these all the time

•The internet deals in strings

•Much like array functions, there are quite a few

strlen()

•How long is a string, in characters?

•As long as this isn’t UTF-8-ish

substr()

•Get a smaller part of the whole string

•Operates by “index”

str_replace()

•search and replace strings within strings

•use arrays for extra power

strpos()

• Finds out the “index” location of a string within a string

• Commonly used to find if a string exists within another

Changing Case

explode()

•Split up a string on certain characters and give back an array of the pieces

implode()

•Build a string from an array

Functions

•Functions are ways to encapsulate & organize your code

•Hundreds of built-in functions

•Calculate values, perform repetitive tasks, output data

Write Your Own Functions

Include

•Load another PHP file into the current contexts

•Executes that code as if it were in the current file

•Gives a warning if the file is not found

Include_Once

•The same as include, except keeps track of if you’re already included the file and only includes it once

•Use but don’t abuse, there is an implicit speed penalty for doing this

Require

•Functions the same way as include except gives a fatal error if the file is not found

•Tends to be used for system components vs. small output snippets

•Require_once == include_once