Cosc 4750

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Cosc 4750

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String String data is always in double quotes ... echo $car; /body /html Constants. Don't use $, instead use a special keyword to create them ... – PowerPoint PPT presentation

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Title: Cosc 4750

1
Cosc 4750

Beginning PHP

2
PHP

PHP gt "PHP Hypertext Preprocessor"
Designed for the web
Cross-platform Runs on both UNIX and windows
(with everything installed correctly)
PHP is mix of PHP langauge and HTML code
Runs on the Sever-side, specifically on the web
server
Light weight compared to PERL, since it runs
inside the web-server itself.
In many ways PHP is perl, but stripped down with
most of the "web" modules already installed.

3
NOTE

I'm assuming you know several things
HTML
SQL
PERL
I'll use PERL to explain PHP.
Also, all files are saved with the .php extension
on them, instead of .html

4
Example PHP code

file helloworld.php
lthtmlgt
ltheadgt
lttitlegtPHP Testlt/titlegt
lt/headgt
ltbodygt
lt?php
echo "ltpgtHello Worldlt/pgt"
?gt
lt/bodygt
lt/htmlgt

Output to browser
lthtmlgt
ltheadgt
lttitlegtPHP Testlt/titlegt
lt/headgt
ltbodygt
ltpgtHello Worldlt/pgt
lt/bodygt
lt/htmlgt

5
Comments

PHP has single line comments like C
uses the // to start a comment
// This is a comment
var 10 //bah bah

6
variables

like PERL
All variables start with a
Unlike PERL
Variables can be typed or typeless
types
String String data is always in double
quotes
integer, double, array (numeric and hash index),
object, and unknown type
Boolean (value true or false)
Displaying variables
echo variablename

7
Using Variables

Remember this is inside html code!
lthtmlgtltbodygt
lt? php
CarType "Ford"
enginesize "3.0"
car cartype . " " . enginesize
echo car
?gt
lt/bodygt
lt/htmlgt

8
Constants

Don't use , instead use a special keyword to
create them
define(constantname, value)
Examples
define("FREEZING", 0)
define(INDEPENCEDAY, "4th of July")
echo "Independence Day is ". INDEPENDENCEDAY

9
Variables and operators

Same as with PERL
With typed variables
numeric operators for numeric data types
string operators for string data types
such as the dot is used for concatenation with
strings
can not str str1 str2

10
Getting data from forms

ltform action"test.php" methodGETgt
lt! Example input box--gt
ltinput NAME"var1" Type"text"gt
lt/formgt
OR
ltform action"test.php" methodPOSTgt
ltinput NAME"var1" Type"text"gt
lt! Example input box--gt
lt/formgt
The name comes into the PHP script as a variable
lt?php
echo var1
?gt
NOTE The name must be the same including case!

11
Radio buttons and Check Box

ltinput name"choice" type"Checkbox"gt
check boxes have the value of on or off
unless you use the value tag
ltinput name"choice" type"Checkbox"
value"Computers"gt
Same with Radio buttons.

12
Filling arrays from forms

ltform methodget action"test2.php"gt
ltinput namearr typetextgt
ltinput namearr typetextgt
ltinput typesubmitgt
lt/formgt
In test2.php
arr0 has the value of the first input and
arr1 has the value from the second.

13
HTML code input

To better "secure" your input you can use a the
function HTMLSpecialChars(value)
This convert html codes into text for display.
string HTMLSpecialChars("ltBgthilt/Bgt")
echo string
Will display ltBgthilt/bgt to the web browser instead
of hi.

14
Control Structures

If statements
Again like PERL
if (boolean value) statements
elseif (boolean value) statements
else statements
Boolean operators are the same as in PERL, except
you don't have to make any distinctions between
string and numerical operators
lt lt gt gt !, AND, , OR, , ! (NOT)

15
Control Structures (2)

switch statement
NOT in perl, just like the C/C statement
switch (variable)
case value1 statements break
case value2 statements break
default statements
like C/C you can leave off the break

16
Control Structures (3)

Loops
while (boolean expression)
statements
do
statements
while (boolean expression)

17
Control Structures (4)

for loops
for (set loop counter test loop counter
increment/decrement loop counter)
statements

18
Arrays structure

foreach structure
similar to PERL
foreach (array As variable)
statements
foreach (array As arrIndex gt var)
statements
second format makes the array index value
available in the loop as well.

19
More on Arrays

Initialization (with number index values)
arr0 "value1"
arr1 "value2"
OR allow PHP fill in the numbers
arr "value1"
arr "value2"
OR
arr array ("value1", "value2", , "valueX")
OR (for hashing)
arr"v1" "value1"
arr"v2" "vavlue2"

20
More on Arrays (2)

Iterating through non-sequential arrays and hash
arrays.
list and each functions
while ( list(indexvalue, element) each(
array) )
echo "The value of element indexvalue is
element"

21
More on Arrays (3)

sorting (with index as numbers)
sort(array)
sorting hash array
asort(hasharray)
NOTE you can use sort on hashes, but the keys
(string indices) are replaced with numbers.
reverse alphabetical order sort
rsort(array) and arsort(hasharray)
ksort(hasharray)
Sorts based on the keys, instead of the element
contents.

22
More on Arrays (4)

array_push() and array_pop()
Allows you to use an array as a stack.
implode and explode functions
string implode("delimiter", array)
like join statement in PERL
arr explode("delimiter", string)
like split statement in PERL

23
functions

function functionname (parameters)
statements
return
OR
return value //or variable
Calling the function
functionname(parameters)
variable functionname(parameters)

24
functions (2)

pass by value
function f1 (var)
// var can be altered but won't change the
// calling variable
pass by reference
function f2 (var)
//var value will now change the calling
variable

25
functions (3)

default parameter values
function f3 (var2)
//f3 can be called with no parameters
// and var will have the value of 2
parameter order, since you don't have pass values
to the parameters
function f4(v12, v2) statements
f4(12) //v1 12, v2 0

26
functions (4)

Scope of variables
Variables "declared" outside of functions are
global
Variables "declared" inside functions are local
variables to the function
"declared" is the first occurrence of the
variable.

creating global variables in functions uses the
keyword global
global variable
static variables
static variable
the variable will retain it's value between
function calls.

27
functions (5)

final notes.
You can nest functions inside functions
the inner function will cause an error
(redeclaration error) on the second time the
outer function is called.
Recursion
allowed

28
including files

include("filename")
Execute a separate PHP script at the point in the
code
include commonly used PHP functions that can be
called by this script.
define variables and/or constants, etc
Can be text or html that will be displayed.

29
File I/O

similar to PERL file I/O
open
filehandle fopen("filename", mode)
fp fopen("data.txt","r") //read from file
data.txt
modes
"r" read only
"w" for writing only
"a" append, create if doesn't exist.
close
fclose (filehandle)

30
File I/O (2)

reading
variable fread(filehandle,bytes)
data fread(fp, 20) // read 20 bytes from the
file
Writing
fwrite(filehandle, data)
fwrite(fp, "abc")

31
File I/O (3)

c fgetc(fp) read file one character at a time
feof(fp) returns true if it the end of the file
arr file(filename) read in an entire file
Each line is an element in the arr
copy(filename1,filename2) copy f1 to f2
rename(f1, f2) rename f1 to f2
unlink(filename) del filename
may not work in windows
use system or exec function (see PERL for
descriptions)

32
Directory I/O

chdir() change directory
rmdir() delete directory
mkdir() delete directory
opendir() open a directory for "reading"
readdir() read the directory
closedir() close the directory

33
PHP database connectivity

Using mysql as the database to connect to, since
it included with our Redhat installation.
First you need to connect to the database
link_id mysql_connect("localhost", "username",
"password")
like mysql command in unix
mysql u username p password h host

34
PHP database connectivity (2)

Now we need to select the database to use
mysql_select_db("database", link_id)
Where link_id is from the mysql_connect command
mysql command
mysqlgt use database

35
PHP database connectivity (3)

After finishing with the database, you need to
close the connection
mysql_close(link_id)

36
PHP commands For lab 6

lt?php
// make the connection
link_id mysql_connect("localhost", "testacc",
"csteach")
//choose the database
mysql_select_db("webacc", link_id)
//now ready to retreive,modify, or delete data
mysql_close(link_id)
?gt

37
Accessing the database

PHP uses one command to send SQL commands to the
database (for mysql)
result mysql_query("SQL command")
Another to retreive results (from say a select),
one row of data at a time
arr mysql_fetch_row(result)
//gets first row of data
arr mysql_fetch_row(result)
//gets next row of data
etc..

38
With a select

result mysql_query("Select from test")
while(query_data mysql_fetch_row(result))
echo "query_data0 query_data1
queary_data2 ltBRgt"
//prints to the browser the contexts of the table
test, with three rows.

39
With a select (2)

Or can use the field names, for better
readablity.
result mysql_query("Select from test")
while(query_data mysql_fetch_row(result))
echo "query_data"name" query_data"ip"
queary_data"owner" ltBRgt"
//prints to the browser the contexts of the table
test, with three rows.

40
With an Insert

sql "Insert into test values
(csteach31,129.72.218.41,cosc)"
mysql_query(sql)
NOTE lack of return value.
NOTE inserting "odd" characters such as ' as in
I'm won't work.
There is a function to fix it called addslashes
var addslashes("I'm") // result "I\'m"
Removed with the stripslashes() later.

41
Delete and update

Use the same php command
sql "delete from test where name 'k2' "
mysql_query(sql)
sql "update test set ip'129.72.14.123' where
name 'esig' "
mysql_query(sql)

42
results from insert/update/delete

mysql will tell you how many how many rows were
effected by insert, update or delete
There is a function to get that information from
mysql
var mysql_affected_rows(link_id)
var contains a the number of effected rows.

43
example