This document summarizes the agenda and content covered in a PHP session on November 17, 2010. It discusses include and require functions, errors and warnings, string functions like strlen(), substr(), str_replace(), and strpos(), writing custom functions, and includes vs requires. Comments and a note on language constructs vs functions are also briefly covered.

1. Beginning PHP
Session #2
November 17, 2010
Josh Butts

2. Agenda for Today
• Go over Homework #1
• Include & Require
• Errors &Warnings
• String Functions
• WritingYour Own Functions

3. Corrections
• Use “echo $foo”, not “echo($foo)”
• I think we forgot to talk about code
comments, so lets do that now

4. Comments

5. 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

6. String Functions
• You’ll use these all the time
• The internet deals in strings
• Much like array functions, there are quite a
few

7. strlen()
• How long is a string, in characters?
• As long as this isn’t UTF-8-ish

8. substr()
• Get a smaller part of the whole string
• Operates by “index”

9. str_replace()
• search and replace strings within strings
• use arrays for extra power

10. strpos()
• Finds out the “index” location of a string within a string
• Commonly used to find if a string exists within another

11. Changing Case

12. explode()
• Split up a string on certain characters and
give back an array of the pieces

13. implode()
• Build a string from an array

14. Functions
• Functions are ways to encapsulate &
organize your code
• Hundreds of built-in functions
• Calculate values, perform repetitive tasks,
output data

15. WriteYour Own
Functions

16. 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

17. 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

18. 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