1. Four representation forms of PHP fragments.
Standard tags:
short tags: script tags:
2. PHP variables and data types
1)                         $variable , variables start with letters, _, There can be no spaces
2) Assignment $variable=value;
3) Weak type, direct assignment, no need to explicitly declare the data type
4) Basic data types: Integer, Double, String, Boolean, Object (object or class), Array (Array)
5) Special data types: Resource (reference to third-party resources (such as database)), Null (empty, uninitialized variable)
3. Operator
1) Assignment operator: =
2) Arithmetic Operations:+,-,*,/,%(molding)
3) Connection operator:, no matter what the operating number is, it is used as string, and the result returns String
4) Combined Assignment Operators =, *=, /=, -=, %=, .=
5) Automatically Incrementing and Decrementing automatic increase and decrease operators:
(1)$variable+=1 <=>$variable++;$variable-=1 <=>$variable-, just like C language, do other operations first, then ++ or -
(2) ++$variable, -$variable, do ++ or - first, then do other operations
6) Comparison operator: = = (left side equals right side), != (the left side is not equal to the right side), = = = (the left side is equal to the right side, and the data type is the same), >=, >, <, <=
7) Logical operators: ||ó or, &&óand, xor (When there is and only one of the left and right sides is true, return true),!
4. Comments:
Single-line comments: //, #
Multi-line comments: /* */
5. Each statement ends with;, and Same as java
6. Define constants: define(“CONSTANS_NAME”,value)
7. Print statement: print, same as c language
8. Process control statement
1) If statement:
(1) if(expression)
{
//code to excute if expression evaluates to true
}
（2）if(expression)
{
}
else
{
}
(3)if(expression1)
{
}
elseif(expression2)
{
}
else
{
}
2)       swich statement
switch (  expression )
{
case result
// execute this if expression results in result1
break;
case result
// execute this if expression results in results2
break;
default:
// execute this if no break statement
// has been encountered hitherto
}
3) ? Operator:
(expression)?returned_if_expression_is_true:returned_if_expression_is_false;
4) while statement:
(1) while (expression)
{

{
// code to be executed
} while (expression);
5) for statement:
for (initialization expression; test expression; modification expression) {
// code to be executed
}
6) break; continue
9、 Write function
1) Define function ：
function function_name($argument1,$argument2,…) //Formal parameter
{
//function code here;
}
2) Function call
function_name($argument1,$argument2,…); //Formal parameters
3) Dynamic Function Calls:

;
function sayHello() { //Define the function sayHello
print "hello
";
}
$function_holder = "sayHello"; //Assign the function name to the variable $function_holder
$function_holder( ;

$life=42;
function meaningOfLife() {
global $life;
/*Re-declare $life as a global variable here. Accessing global variables within a function must be like this. If the value of the variable is changed within the function, it will be changed in all code fragments*/
print "The meaning of Life is $ live & lt; br & gt; ";
}
Meaningoflife ();
? & gt;
& lt;/body & gt;
& lt;/html & gt; ; T & lt; head & gt;
& lt; title>Listing 6.10


function numberedHeading( $txt ) {
static $num_of_calls = 0;
$num_of_calls++;
print "< ;h1> ;$num_of_calls. $txt";
}
numberedHeading("Widgets"); //When called for the first time, print $num_of_calls value is 1
print("We build a fine range of widgets

");
numberedHeading("Doodads"); /*When called for the first time, print $num_of_calls value is 2, because the variable is static type, static type is resident in memory*/
print("Finest in the world< ;p>");
?>


6) Passing value (value) and passing address (reference):
Passing value: function function_name($argument)
< html>

function addFive( $num ) {
$num += 5;
}
$orignum = 10;
addFive( &$orignum );
print( $orignum );
?>


Result: 10
Address: funciton function_name( &$argument)





function addFive( &$num ) {
$num += 5; /*What is passed is a reference to the variable $num, so changing the value of the formal parameter $num is actually changing the value stored in the physical memory of the variable $orignum*/
}
$orignum = 10;
addFive( $orignum );
print( $orignum );
?>


Result: 15
7) Create an anonymous function: create_function(' string1','string2'); create_function is a PHP built-in function, specially used to create anonymous functions. It accepts two string parameters, the first is the parameter list, and the second is the body of the function

< ;head>



$my_anon = create_function( '$a, $b', 'return $a+$ b;' );
print $my_anon( 3, 9 );
// prints 12
?>


8) Determine whether the function exists: function_exists(function_name), parameters For the function name
10, Use PHP to connect to MySQL
1) Connection: &c
2) Close the connection: mysql_close($conn);
3) Establish connection between the database and the connection: mysql_select_db(database name, connection index);
4 ) will The SQL statement is executed for MySQL: $result = mysql_query($sql, $conn); //Add, delete, modify and query are all like this
5) Retrieve data: Return the number of records: $number_of_rows = mysql_num_rows($result);
Put the records Enter the array: $newArray = mysql_fetch_array($result);
Example:
// open the connection
$conn = mysql_connect("localhost", "joeuser", "somepass");
// pick the database to use
mysql_select_db("testDB",$conn);
// create the SQL statement
$sql = "SELECT * FROM testTable";
// execute the SQL statement
$result = mysql _query($sql, $conn ) or die(mysql_error());
//go through each row in the result set and display data
while ($newArray = mysql_fetch_array($result)) {
// give a name to the fields
$id = $ newArray['id'];
          $testField  =  $newArray['testField']; 
                                                                                                                                                                                            newArray['id'];
?>
11. Accept form elements: $_POST[form element name],
such as ó$_POST[user]
Accept the queryString value in the url (GET method): $ _GET[queryString]
12. Go to other pages: header("Location: http://www.samspublishing.com");
13. String operations:
1) explode("-",str)ósplite in Java
2) str_replace ($str1, $str2, $str3) => $str1 is the string to be found, $str2 is the string to replace, $str3 starts to search and replace from this string
3) substr_replace:
14 , session:
1) Open session: session_start(); // You can also set sessi in php.ini
2) Assign value to session: $_SESSION[session_variable_name]=$variable;
3) Access session: $variable =$_SESSION [session_variable_name];
4) Destroy session: session_destroy();
15. Complete example of display classification:
//connect to database
$conn = mysql_connect("localhost", "joeuser", "somepass ")
or die(mysql_error());
mysql_select_db("testDB",$conn) or die(mysql_error());
$display_block = "

My Categories

Select a category to see its items.

";
//show categories first
$get_cats = "select id, cat_title, cat_desc from
store_categories order by cat_title";
$get_cats_res = mysql_query($get_cats) or die (mysql_error());
if (mysql_num_rows($get_cats_res) < 1) { //If the number of returned record rows is less than 1, it means there is no category
$display_block = "

Sorry, no categories to browse.

";
} else {
while ($cats = mysql_fetch_array($get_cats_res)) { //Put the record into the variable $cats
$cat_id = $cats[id ];
$cat_title = strtoupper(stripslashes($cats[cat_title]));
$cat_desc = stripslashes($cats[cat_desc]);
$display_block .= "

href ="$_SERVER[PHP_SELF][U1] ?cat_id=$cat_id">$cat_title//Click this url to refresh this page. Line 28 reads cat_id and displays the corresponding category. Item

$cat_desc

";
if ($_GET[cat_id] == $cat_id) { //Select a category and see the items below
//get items
$get_items = "select id , item_title, item_price
from store_items where cat_id = $cat_id
order by item_title";
$get_items_res = mysql_query($get_items) or die(mysql_error());
if (mysql_num_rows($get_items_res ) < 1) {
$ display_block = "

Sorry, no items in
this category.

";
} else {
$display_block .= "

";
while ($items = mysql_fetch_array($get_items_res)) {
$item_id = $items[id];
$item_title = stripslashes($items[item_title]);
$item_price = $items[item_price];
$display_block .= "
• = "

";
}
}
}
}
?>




< ;BODY>



16. PHP connection Access:
$dbc=new com("adodb.connection") ;
$dbc->open("driver=microsoft access driver (*.mdb);dbq=c:member.mdb");
$rs=$dbc->execute("select * from tablename");
$i=0;
while (!$rs->eof){
$i+=1
$fld0=$rs->fields["UserName"];
$fld0=$rs->fields[ "Password"];
....
echo "$fld0->value $fld1->value....";
$rs->movenext();
}
$rs->close();
?>

The above introduces the theoretical basis of the debit and credit accounting method. This is a good basic PHP study note, including the theoretical basis of the debit and credit accounting method. I hope it will be helpful to friends who are interested in PHP tutorials.