PHP notes--java programmer to read PHP program

1. PHP is a server-side scripting language with a loosely typed language.

2. ?> XML style

scripting style

?> short style

<% %> ASP style

in ; end;

3. notes:

a) //

b) #

c) /* */

4. variables are containers that store data and are case-sensitive. When the variable is very long, use the delimiter <<<.

$k =<<<>< span=""><>

...

Str

thought PHP is a loosely typed language, so variables do not have specific type keywords at the time of declaration.

Unified Use $ Start + Variable name

1. must have letters or _ Start

2. can only contain alphanumeric characters and underscores

3. sensitive to case

5. variables can be PHP The script is declared at any location.

6. is referenced / script to use-scope

a) Local ( partial )

b) Global ( globally )

c) static ( statically )

variables declared outside of a function have Global scope, which can only be accessed outside of the function.

variables declared inside a function have Local Scope , which can only be accessed within a function.

function Internal Call Global variables need to be ① internally with Global keywords to declare; ② $GLOBAL [index] All global variables can be stored in a hyper-global variable $GLOBAL [index] obtained in the.

7. $GLOBAL [index] This array is accessible within the function and can be used to update global variables directly.

8. Typically, when a function finishes executing, all variables are deleted. If you do not need to delete, you need to use the static when you first declare

9. constant None $, The value cannot be changed in the script. by define (" name of the constant" , " constant value ", " constant name is case sensitive true ( same case ) insensitive ,false sensitive. Define constants in the class with the const keyword.

A constant that changes according to the position used, and becomes the magic constant.

1) __file__ current folder

2) __line__ Current number of rows

3) __function__ Current function name

4) __class__ Current class name

5) __method__ The method name of the current object

. Print: echo capable of outputting more than one string.

Print Only One string can be output, and always returns 1.

One by one . string Length strlen (); retrieves the specified character or text within a string Strpos (); string connection with " . " , " . "followed by a number must be a space.

. Super Global variables:

a) $GLOBALS references all variables in the global scope.

b) $_server holds information about the header, path, and location of the script.

c) $_request is used to collect Data submitted by HTML forms.

D) $_post is widely used to collect submitted method= "POST" The form data after the HTML form is also commonly used with transitive variables.

e) $_get is used to collect the submitted HTML form (method= "GET" ) After the form data, you can also collect The data sent in the URL.

f) $_files uploads files from the client computer to the remote server.

g) $_env Gets the server-side environment parameters. (Variables_order=epgcs)

h) $_cookie is used to retrieve The value of the COOKIE.

i) $_session is used to store information about a user's session, or to change settings for a user session.

. Include/require statement gets all the text that exists in the specified file / Code / tag, and copy it to the Include/require statement in the file.

a) require ( static loading ), when an error occurs, generates a fatal error and stops the script.

b) include ( dynamic load ),When an error occurs, only a warning is generated, and the script continues execution.

c) require_once/include_once The same page is included only once.

. Array Processing: $ Array name [' Key name '] to initialize the array, or you can Array () function to create an array.

count () Returns the length of the array.

Array Traversal: foreach cycle, with count () get the length of the array and then use for;list () language structure loops, only for default numeric indexes ; each () a key-value pair is returned.

while (list ($key, $value) =each ($array)) {

}

foreach ($array as $key = = $value) {

}

A . PHP in the class object with class keyword to declare that the properties of a class also have scope, and do not specify scopes that can be used var The difference between a member method and a function is that it can be decorated with a keyword. Constructor __constract, destructor __destruct

. " :: " a scope operator that can invoke constants, variables, and methods in a class without instantiation;

" = " array member access symbols;

" - " object member access symbols;

" =& " references (aliases);

" = " assigned value.

. $ Variable name = new class name ([ parameter ]); // instantiation;

$ Variable name - member Properties = value ; // Assign a value to the attribute;

$ Variable name - member Properties ; // get attribute value;

$ Variable name - member Methods ; // use method;

. MySQL : General use conn.php package, and then use require to the desired page.

1) $conn = mysql_pconnect ("localhost", "root", "") or Die (Mysql_error ());

2) mysql_select_db (" database name ", $conn);// connect to the specified database.

3) mysql_query ("Set names UTF8");

4) $sql = "";

5) $resultSet = mysql_query ($sql) or Die ("Invalid query:". mysql_error);// return sql statement result set;

6) while ($v = mysql_fetch_array ($resultSet)) {

7) echo " field Name:". $v [' title '];

8) }

9) mysql_free_result ($resultSet);// close result set;

Ten) mysql_close ($conn);// close Connection

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