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====== PHP code ======
PHP Editor:
  * Notepad++: http://notepad-plus-plus.org/download/v6.6.3.html
  * Eclipse pdt: [[php:eclipsepdt|Eclipse PDT(PHP Development Tool)]]
===== Create PHP simple code and run =====
==== Create helloworld.php ====
<code php>
<?php
  print "Hello Web!";
?>
</code>
==== Create phpinfo.php =====
<code php>
<?php
  phpinfo();
?>
</code>
==== Run PHP code ====
  * linux: <code bash>
php helloworld.php
</code>
  * windows: <code dos>
c:\Program Files (x86)\PHP\php.exe helloworld.php
</code>
===== How to debug in PHP and Javascript =====
==== Config debug mode in PHP ====
check http://192.168.2.11/info.php(To run with debug mode, **remove option --disable-debug** when build PHP from source). In php.ini, we need turn on **log_errors = On** for production and development and where to save log file<code>
error_log = /var/log/php_errors.log
</code>To be can save log to php_errors.log, you must change own to allow http write log:<code bash>
chown www.www /var/log/php_errors.log
</code>
Config turn on/off debug log in **php**:
  * default production [/etc/php.ini]:<code>
error_reporting = E_ALL & ~E_DEPRECATED
display_errors = Off
display_startup_errors = Off
track_errors = Off
</code>  
  * debug: [/etc/php.ini]<code>
error_reporting = E_ALL
display_errors = On
display_startup_errors = On
track_errors = On
</code>
  * Explain config:display_errors = On => Allow display debug information in front end
Config turn on debug log in **ngix with php-fpm backend**:
  * in php-fpm.conf<code>
[global]
error_log = /var/log/php-fpm.log
;log_level = notice
[www]
catch_workers_output = yes
</code>
  * in php.ini:<code ini>
display_errors = On ⇒ Allow display debug information in front end
</code>
Config turn on/off log in httpd:
  * [/etc/httpd/conf.d/php.conf]<code>
php_flag  display_errors        on
php_value error_reporting       2039
</code>
  * Turn on in PHP code for debugging:<code php>
error_reporting(E_ALL & ~E_NOTICE);
if (!ini_get('display_errors')) {
    ini_set('display_errors', '1');
}
</code>
  * Turn error log in httpd.conf<code bash>
ErrorLog "logs/error_log"
LogLevel error
</code>
==== Debug error in nginx with php-fpm ====
You set it per pool, inside: **/etc/php/8.x/fpm/pool.d/www.conf**
<code>
[www]
................
catch_workers_output = yes
php_admin_flag[log_errors] = on
php_admin_value[error_log] = /var/log/php8.2-fpm.log
</code>
Then restart PHP-FPM

Example Before vs After
  * Before (catch_workers_output = no):<code>
[10-Nov-2025 10:30:21] WARNING: [pool www] child 12345 exited on signal 11 (SIGSEGV)
</code>👉 You only see a generic signal crash.
  * After (catch_workers_output = yes):<code>
[10-Nov-2025 10:30:21] WARNING: [pool www] child 12345 said into stderr: "PHP Fatal error: Uncaught Error: Call to undefined function get_header() in /var/www/html/wp-content/themes/flatsome/page.php:12"
</code>
✅ Now you can see the exact file and line that crashed WordPress.
🛠️ Combine With These for Full Debugging, Inside the same pool file or your **php.ini**:<code ini>
log_errors = On
error_reporting = E_ALL
display_errors = Off
</code>
==== Config in web server to display error log ====
  * in nginx<code>
###demo.vn
server {
    listen       80;
    server_name  demo.vn www.demo.vn;
    root   /data/www/gamebai/demo;

    index index.html index.htm index.php;
    fastcgi_index  index.php;

    access_log /gb/nginx/logs/demo.access_log;
    error_log /gb/nginx/logs/demo.error_log;

    error_page  404              /404.html;
    error_page 500 502 503 504  /50x.html;

    location ~* "^.+\.(js|ico|gif|jpg|png|css|swf|htc|xml|bmp)$" {
        access_log  off;
        expires     30d;
    }
    location ~ \.php$ {
      fastcgi_pass   127.0.0.1:9000;
      fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
      include        fastcgi_params;
    }
}
</code> => error log: error_log /gb/nginx/logs/demo.error_log;
  * in apache<code>
<VirtualHost *:80>
  DocumentRoot "D:/web/gamebai/demo"
  ServerName demo.vn
  DirectoryIndex index.php index.html index.htm
  <Directory D:/web/gamebai/demo>
    Options Indexes FollowSymLinks MultiViews
    AllowOverride all
    Order Deny,Allow
    Allow from all
  </Directory>  
  ErrorLog "logs/demo-error.log"
  CustomLog "logs/demo-access.log" common
</VirtualHost>
</code> => error log: ErrorLog "logs/demo-error.log"
==== Debug with php code ====
  * Debug with print<code php>
print(variable_name)
</code>
  * Debug with firebug
      * Config addon firebug in firefox: enable console pannel and net pannel
  * var_dump<code php>
echo "<pre>";var_dump(debug_backtrace());echo "</pre>";
</code> => Print name of class for checking their functions
  * using try catch to get error and write to log:<code php>
    try{
  
    }
    catch(Exception $e){
        echo $e->getMessage();
    }
?>
</code>
==== Debug with xdebug ====
Refer: [[php:xdebug|Debug PHP with xdebug]]

==== Debug with Javascript ====
  * Debug with Internet Explorer: Turn on Debug Mode in Internet Options for debugging code javascript error
  * Debug in Chrome: Using Developer Tools for debugging Javascript with break points
===== PHPUnit =====
refer: https://phpunit.de/getting-started/phpunit-5.html
==== Install PHPUnit ====
  * Install as binary<code bash>
wget -O phpunit https://phar.phpunit.de/phpunit-5.phar
chmod +x phpunit
./phpunit --version
</code>
  * Install with composer:<code bash>
composer require --dev phpunit/phpunit ^5
./vendor/bin/phpunit --version
</code>
==== Run PHPUnit ====
===== PHP Slow Log Config =====
==== Config Slow Log in php-fpm ====
<code>
request_slowlog_timeout = 5s
slowlog = /var/log/php-fpm/slowlog-site.log
</code>
==== Config Slow Log for php ====
===== Basic Syntaxs =====
==== PHP tags ====
  * standard tags:<code php> <?php ?></code>
  * short tags: <code php><? ?></code>
  * ASP tags: <code php><% %></code>
  * script tags: <code php><SCRIPT LANGUAGE="php"> </SCRIPT></code>
The standard and the script tags are guaranteed to work under any configuration, the other tags be enabled in your "php.ini"
==== Comment in PHP code ====
<code php>
//your commment
#your commment
/*your commment
*/
</code>
==== php with html ====
=== write code php with <?php -and- ?> tags ===
<code php>
<html>
 <title>HTML with PHP</title>
 <body>
 <h1>My Example</h1>
 
<?php
 //your php code here
?>
<b>Here is some more HTML</b>

<?php
 //more php code
?>
</body>
</html>
</code>
=== output HTML with PHP by using PRINT or ECHO ===
<code php>
<?php 
  Echo "<html>";
  Echo "<title>HTML with PHP</title>";
  Echo "<b>My Example</b>";
  //your php code here
  Print "<i>Print works too!</i>"; 
?>
</code>
==== variable and constant in PHP ====
=== set value for variable ===
<code php>
if (! isset($cars)) { $cars = $default_cars; }
$defaults = array('emperors'  => array('Rudolf II','Caligula'),
                  'vegetable' => 'celery',
                  'acres'     => 15);
</code>
=== static variable ===
If you want a local variable to retain its value between invocations of a function, Declare the variable as static:
<code php>
function track_times_called( ) {
    static $i = 0;
    $i++;
    return $i;
}
</code>
=== global variable ===
  * Bring the global variable into local scope with the global keyword: <code php>
function eat_fruit($fruit) {
   global $chew_count;
 
   for ($i = $chew_count; $i > 0; $i--) {
     ...
   }
}
</code>
  * Or reference it directly in $GLOBALS:<code php>
function eat_fruit($fruit) {
   for ($i = $GLOBALS['chew_count']; $i > 0; $i--) {
     ...
   }
}
</code>

=== Magic constants ===
<code>
__LINE__ 	The current line number of the file.
__FILE__ 	The full path and filename of the file.
__DIR__ 	The directory of the file.
__FUNCTION__ 	The function name.
__CLASS__ 	The class name. (Added in PHP 4.3.0) As of PHP 5 this constant returns the class name as it was declared (case-sensitive). In PHP 4 its value is always lowercased.
__METHOD__ 	The class method name. (Added in PHP 5.0.0) The method name is returned as it was declared (case-sensitive).
__NAMESPACE__ 	The name of the current namespace (case-sensitive). This constant is defined in compile-time (Added in PHP 5.3.0). 
DIRECTORY_SEPARATOR
	"..".DIRECTORY_SEPARATOR."foo" => windows: "..\foo" and linux: "../foo"
</code>
==== Function in PHP ====
=== simple function ===
<code php>
function add($a, $b) {
  return $a + $b;
}
$total = add(2, 2);
</code>
=== Setting Default Value and Reference variable in function ===
  * Default value<code php>
function wrap_html_tag($string, $tag = 'b') {
  $string = "<$tag>$string</$tag>";
  return $string;
}
$string = 'I am some HTML';
wrap_html_tag($string);
print "$string\n";
$string = wrap_html_tag($string);
print "$string\n";
</code>Out put:<code>
I am some HTML
<b>I am some HTML</b>
</code>
  * reference value<code php>
function wrap_html_tag(&$string, $tag = 'b') {
  $string = "<$tag>$string</$tag>";
  return $string;
}
$string = 'I am some HTML';
wrap_html_tag($string);
echo $string;
</code>Out put:<code>
<b>I am some HTML</b>
</code>
==== include code with require and include ====
require and include. The main difference is that attempting to require a nonexistent file is a fatal error, while attempting to include such a file produces a warning but does not stop script execution.
<code php>
<? include 'header.html'; ?>
content
<? include 'footer.html'; ?>

<? require 'codelib.inc'; ?>
mysub(  );// defined in codelib.inc
</code>
===== PHP Cookies and session =====
In order to store the contents of a shopping cart while the user is browsing your site, There are two easy ways: you either use cookies or sessions.
==== PHP cookies ====
=== Understand about cookies ===
  * Cookies are small amounts of data stored by the user's browser after a request from a server or script
      * the maximum number of cookies from a host that can be stored by a browser is 20
      * and the maximum cookie size is 4KB
      * Cookies consist of a name, value, expiry date, host and path information, and they end up to the user because they are send from the server thru an HTTP header
=== get, set and delete the cookie ===
  * There are 3 ways a PHP script can access the cookie: 
      * Using the environmental variable "$HTTP-COOKIE"  which holds all cookie names and values
      * In a global variable "$cookie_name" (replace with the name, of course)
      * Or in the global array variable "HTTP_COOKIE_VARS["cookie_name"]":Example:<code php>	
print $HTTP_COOKIE; //outputs "visits=23"
print getenv("HTTP_COOKIER"); //outputs "visits=23"
print $visits; //outputs "23"
print $HTTP_COOKIE_VARS[visits]; //outputs "23"
</code>
  * To set a cookie with PHP, you can use the "header()" function, or the "setcookie()" function:<code php>
//don't output anything before this
header("visits=23; expires=Friday, 20-Aug-04 03:27:21 GMT; path=/; domain=softwareprojects.org");
setcookie("hits", 23, time() + 3600, "/","softwareprojects.org", 0); //notice this last extra argument
</code>
  * Deleting cookies is also very easy, you should set the cookie you want to delete a date that has already expired.<code php>
setcookie("visits", 23, time(), 60, "/", "softwareprojects.org", 0)
</code>
==== PHP Session ====
=== Understand about PHP Session ===
  * The difference between sessions and cookies is that a session can hold multiple variables, and you don't have to set cookies for every variable.
  * By default, the session data is stored in a cookie with an expiry date of zero, which means that the session only remains active as long as the browser. When you close the browser, all the stored information is lost. You can modify this behavior by changing the "session.cookie_lifetime" setting in "php.ini" from zero to whatever you want the cookie lifetime to be.
  * PHP uses several functions to deal with sessions. Before you start the actual work with sessions, you must explicitly start a session with "session_start()"
=== get, set and remove session variable ===
  * Set value session variable<code php>
session_start();
if(isset($stored_var))//if(session_is_registered("stored_var"))
{
  print $stored_var; //this will not be displayed the first time you load the page, because you haven't registered the variable yet!
}
else
{
  $stored_var = "Hello from a stored variable!";
  session_register("stored_var"); //don't do this: session_register($session_var)
}
</code>
  * Remove the registered variable<code php>
session_start();
session_register("test");
$test = 12;
session_unset(); //$test is destroyed
session_destroy();
print $test; //outputs nothing
</code>
===== PHP connect Database =====
<code php>
if(!mysql_connect("localhost", "bob", "secret")) //tries to connect to the database server
die("Unable to connect to the database server!"); //terminates the script, and outputs the error
</code>
==== PHP mysql ====
<code php>
'connect'            => 'mysql_connect',
'pconnect'           => 'mysql_pconnect',
'select_db'          => 'mysql_select_db',
'query'              => 'mysql_query',
'query_unbuffered'   => 'mysql_unbuffered_query',
'fetch_row'          => 'mysql_fetch_row',
'fetch_array'        => 'mysql_fetch_array',
'fetch_field'        => 'mysql_fetch_field',
'free_result'        => 'mysql_free_result',
'data_seek'          => 'mysql_data_seek',
'error'              => 'mysql_error',
'errno'              => 'mysql_errno',
'affected_rows'      => 'mysql_affected_rows',
'num_rows'           => 'mysql_num_rows',
'num_fields'         => 'mysql_num_fields',
'field_name'         => 'mysql_field_name',
'insert_id'          => 'mysql_insert_id',
'escape_string'      => 'mysql_escape_string',
'real_escape_string' => 'mysql_real_escape_string',
'close'              => 'mysql_close',
'client_encoding'    => 'mysql_client_encoding',
'ping'               => 'mysql_ping',
</code>
==== PHP mysqli ====
<code php>
'connect'            => 'mysqli_real_connect',
'pconnect'           => 'mysqli_real_connect', // mysqli doesn't support persistent connections THANK YOU!
'select_db'          => 'mysqli_select_db',
'query'              => 'mysqli_query',
'query_unbuffered'   => 'mysqli_unbuffered_query',
'fetch_row'          => 'mysqli_fetch_row',
'fetch_array'        => 'mysqli_fetch_array',
'fetch_field'        => 'mysqli_fetch_field',
'free_result'        => 'mysqli_free_result',
'data_seek'          => 'mysqli_data_seek',
'error'              => 'mysqli_error',
'errno'              => 'mysqli_errno',
'affected_rows'      => 'mysqli_affected_rows',
'num_rows'           => 'mysqli_num_rows',
'num_fields'         => 'mysqli_num_fields',
'field_name'         => 'mysqli_field_tell',
'insert_id'          => 'mysqli_insert_id',
'escape_string'      => 'mysqli_real_escape_string',
'real_escape_string' => 'mysqli_real_escape_string',
'close'              => 'mysqli_close',
'client_encoding'    => 'mysqli_client_encoding',
'ping'               => 'mysqli_ping',
</code>
==== Convert from mysql to mysqli ====
Using tool: https://github.com/philip/MySQLConverterTool
<code bash>
php MySQLConverterTool-master/cli.php -f changeusername.php > changeusername_new.php
</code>
And Modify some missing in tool:<code php>
mysqli_connect("127.0.0.1", "forum_ttb", "xxxxxxxxxx"));
</code>to<code php>
=> mysqli_connect("127.0.0.1", "forum_ttb", "xxxxxxxxxx","forum_ttb"));
</code>
===== PHP curl =====
<code php>
<?php
function curl_post($url, $vars=array(), $second=10)
{
    try{
        $ch = curl_init();
        if ($ch === false) {
            throw new Exception('failed to initialize');
        }
        curl_setopt($ch,CURLOPT_TIMEOUT,$second);
        curl_setopt($ch,CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch,CURLOPT_URL,$url);
        curl_setopt($ch,CURLOPT_POST, 1);
        curl_setopt($ch,CURLOPT_POSTFIELDS,$vars);
        $data = curl_exec($ch);
        if ($data === false) {
            throw new Exception(curl_error($ch), curl_errno($ch));
        }
        curl_close($ch);
    }catch(Exception $e){
        echo "Curl Error: " . $e->getCode . $e->getMessage();
    }
    if($data)
        return $data;
    else
        return false;
}
</code>