Very teachable. Improve PHP code quality by 36 _php skills

Source: Internet
Author: User
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1. Do not use relative paths
You will often see:
Require_once ('.. /.. /lib/some_class.php ');
There are many drawbacks to this approach:
It first finds the specified PHP include path, and then finds the current directory.
Therefore, too many paths are checked.
If the script is contained by a script in another directory, its base directory becomes the directory where another script resides.
Another problem is that when a timed task runs the script, its parent directory may not be a working directory.
So the best option is to use an absolute path:
Define (' ROOT ', '/var/www/project/');
Require_once (ROOT. '.. /.. /lib/some_class.php ');
Rest of the code
We have defined an absolute path, and the value is written dead. We can also improve it. Path/var/www/project may also change, so do we have to change it every time? No, we can use __file__ constants, such as:
Suppose your script is/var/www/project/index.php
Then __file__ 'll always have this full path.
Define (' ROOT ', PathInfo (__file__, pathinfo_dirname));
Require_once (ROOT. '.. /.. /lib/some_class.php ');
Rest of the code
Now, no matter which directory you move to, such as moving to an extranet server, the code can run correctly without changing it.
2. Do not use require directly, include, Include_once, required_once
You can introduce multiple files, such as class libraries, tool files, and helper functions, in the script header, such as:
Require_once (' lib/database.php ');
Require_once (' lib/mail.php ');
Require_once (' helpers/utitlity_functions.php ');
This usage is quite primitive. should be more flexible. You should write an assistant function containing the file. For example:
function Load_class ($class _name)
{
Path to the class file
$path = ROOT. '/lib/'. $class _name. '. php ');
Require_once ($path);
}
Load_class (' Database ');
Load_class (' Mail ');
Is there anything different? The code is more readable.
You can extend the function on demand, such as:
function Load_class ($class _name)
{
Path to the class file
$path = ROOT. '/lib/'. $class _name. '. php ');
if (file_exists ($path))
{
Require_once ($path);
}
}
You can do more:
Find multiple directories for the same file
It's easy to change the directory where the class files are placed, without having to modify one by one of the code everywhere
You can use similar functions to load files, such as HTML content.
3. Keep Debug code for application
In the development environment, we print the database query statements, dump the variable values of the problem, and once the problem is resolved, we annotate or delete them. A better practice, however, is to keep the debug code.
In the development environment, you can:
Define (' Environment ', ' development ');
if (! $db->query ($query)
{
if (Environment = = ' development ')
{
echo "$query failed";
}
Else
{
echo "Database error. Please contact administrator ";
}
}
In the server, you can:
Define (' environment ', ' production ');
if (! $db->query ($query)
{
if (Environment = = ' development ')
{
echo "$query failed";
}
Else
{
echo "Database error. Please contact administrator ";
}
}
4. Use Cross-platform functions to execute commands
System, exec, PassThru, shell_exec these 4 functions can be used to execute systems commands. Every action has a slight difference. The problem is that when in a shared host, some functions may be selectively disabled. Most beginners tend to check which function is available at a time, but use it again.
A better solution is to marshal the function into a cross-platform function.
/**
Execute a command in the terminal
Uses:
1. System
2. PassThru
3. exec
4. Shell_exec
*/
function Terminal ($command)
{
System
if (function_exists (' System '))
{
Ob_start ();
System ($command, $return _var);
$output = Ob_get_contents ();
Ob_end_clean ();
}
PassThru
else if (function_exists (' PassThru '))
{
Ob_start ();
PassThru ($command, $return _var);
$output = Ob_get_contents ();
Ob_end_clean ();
}
Exec
else if (function_exists (' exec '))
{
EXEC ($command, $output, $return _var);
$output = implode ("\ n", $output);
}
Shell_exec
else if (function_exists (' shell_exec '))
{
$output = Shell_exec ($command);
}
Else
{
$output = ' Command execution not possible on this system ';
$return _var = 1;
}
Return array (' Output ' => $output, ' status ' => $return _var);
}
Terminal (' ls ');
The above function will run the shell command, as long as a system function is available, which keeps the code consistent.
5. Flexible writing functions
function Add_to_cart ($item _id, $qty)
{
$_session[' cart ' [' item_id '] = $qty;
}
Add_to_cart (' IPHONE3 ', 2);
Use the above function to add a single item. And when you add a list of items, do you want to create another function? No, just a little attention to the different types of parameters, you will be more flexible. Such as:
function Add_to_cart ($item _id, $qty)
{
if (!is_array ($item _id))
{
$_session[' cart ' [' item_id '] = $qty;
}
Else
{
foreach ($item _id as $i _id => $qty)
{
$_session[' cart ' [' i_id '] = $qty;
}
}
}
Add_to_cart (' IPHONE3 ', 2);
Add_to_cart (Array (' IPHONE3 ' => 2, ' IPAD ' => 5));
Now, the same function can handle different types of input parameters. You can refactor your multiple code to make it smarter by referencing the example above.
6. Intentionally ignore PHP close tag
I'd like to know why so many blog posts about PHP recommendations do not mention this.
<?php
echo "Hello";
Now dont close this tag
This will save you a lot of time. Let's give an example:
A super_class.php file
<?php
Class Super_class
{
function Super_function ()
{
Super Code
}
}
?>
Super extra character after the closing tag
index.php
Require_once (' super_class.php ');
Echo an image or PDF, or set the cookie or session data
In this way, you will get a Headers already send error. Why? Because "super extra character" has been exported. Now you have to start debugging. This will take a lot of time to find the location of Super extra.
Therefore, develop the habit of omitting the closing character:
<?php
Class Super_class
{
function Super_function ()
{
Super Code
}
}
No closing Tag
It would be better.
7. Collect all input at one place, output to browser at a time
This is called the output buffer, if you have already output the content in a different function:
function Print_header ()
{
echo "<div id= ' header ' >site Log and Login links</div>";
}
function Print_footer ()
{
echo "<div id= ' footer ' >site is made by me</div>";
}
Print_header ();
for ($i = 0; $i < $i + +)
{
echo "I is: $i <br/> ';"
}
Print_footer ();
Alternative, where the output is collected centrally. You can store it in a local variable of a function, or you can use Ob_start and Ob_end_clean. As follows:
function Print_header ()
{
$o = "<div id= ' header ' >site Log and Login links</div>";
return $o;
}
function Print_footer ()
{
$o = "<div id= ' footer ' >site is made by me</div>";
return $o;
}
Echo Print_header ();
for ($i = 0; $i < $i + +)
{
echo "I is: $i <br/> ';"
}
Echo Print_footer ();
Why output buffering is required:
>> can change the output before sending it to the browser. such as the Str_replaces function or may be preg_replaces or add some monitoring/debugging HTML content.
>> output to the browser while doing PHP processing is very bad. You should have seen an error message in the sidebar or in the middle of some sites. Do you know why it happened? Because processing and output are mixed.
8. Send the correct MIME type header information if the output is not HTML content.
Output some XML.
$xml = ' <?xml version= ' 1.0 ' encoding= ' utf-8 ' standalone= ' yes '?> ';
$xml = "<response>
<code>0</code>
</response> ";
Send XML data
Echo $xml;
Work well. But some improvements are needed.
$xml = ' <?xml version= ' 1.0 ' encoding= ' utf-8 ' standalone= ' yes '?> ';
$xml = "<response>
<code>0</code>
</response> ";
Send XML data
Header ("Content-type:text/xml");
Echo $xml;
Note Header line. The line tells the browser to send the content of the XML type. So the browser can handle it correctly. Many JavaScript libraries also rely on header information.
Similar to JavaScript, CSS, jpg image, PNG image:
Javascript
Header ("Content-type:application/x-javascript");
echo "var a = 10";
Css
Header ("Content-type:text/css");
echo "#div ID {background: #000;}";
9. Set the correct character encoding for the MySQL connection
Have encountered in the MySQL table set unicode/utf-8 encoding, Phpadmin can also be displayed correctly, but when you get the content and output in the page, there will be garbled. Here's the problem with the character encoding of the MySQL connection.
Attempt to connect to database
$c = Mysqli_connect ($this->host, $this->username, $this->password);
Check Connection Validity
if (! $c)
{
Die ("Could not connect to the" database host: <br/> ". Mysqli_connect_error ());
}
Set the character set of the connection
if (!mysqli_set_charset ($c, ' UTF8 '))
{
Die (' Mysqli_set_charset () failed ');
}
Once the database is connected, it is best to set the characterset of the connection. If your application is to support multiple languages, it is necessary to do so.
10. Use Htmlentities to set the correct encoding options
Before php5.4, the character's default encoding is iso-8859-1 and cannot be directly output such as Àâ.
$value = Htmlentities ($this->value, ent_quotes, CHARSET);
After php5.4, the default encoding is UTF-8, which will solve many problems. But if your application is multilingual, still pay attention to coding problems.
11. Do not use gzip compression output in the application, let Apache processing
Have you considered using Ob_gzhandler? Don't do that. It doesn't make any sense. PHP applies only to write applications. You should not worry about server and browser data transfer optimization issues.
Use Apache's Mod_gzip/mod_deflate module to compress content.
12. Output dynamic JavaScript content using Json_encode
PHP is often used to output dynamic JavaScript content:
$images = Array (
' Myself.png ', ' friends.png ', ' colleagues.png '
);
$js _code = ';
foreach ($images as $image)
{
$js _code. = "' $image '";
}
$js _code = ' var images = ['. $js _code. ']; ';
echo $js _code;
Output is var images = [' Myself.png ', ' friends.png ', ' colleagues.png ',];
Smarter way to use Json_encode:
$images = Array (
' Myself.png ', ' friends.png ', ' colleagues.png '
);
$js _code = ' var images = '. Json_encode ($images);
echo $js _code;
Output Is:var images = ["Myself.png", "Friends.png", "Colleagues.png"]
Elegant?
13. Check directory Write permissions before writing files
Before you write or save the file, make sure that the directory is writable, if not writable, and output error messages. This will save you a lot of debugging time. Linux system, the need to process permissions, directory permissions will cause a lot of problems, files may not read and so on.
Make sure your application is smart enough to output some important information.
$contents = "All content";
$file _path = "/var/www/project/content.txt";
File_put_contents ($file _path, $contents);
This is generally true. But there are some indirect problems. File_put_contents may fail for several reasons:
>> Parent Directory does not exist
>> directory exists, but not writable
>> files are written and locked?
So it's better to make a clear check before writing a file.
$contents = "All content";
$dir = '/var/www/project ';
$file _path = $dir. "/content.txt";
if (is_writable ($dir))
{
File_put_contents ($file _path, $contents);
}
Else
{
Die ("Directory $dir is isn't writable, or does not exist.") Please check ");
}
After doing so, you will get a clear message of where the file is written and why it failed.
14. Change file permissions created by application
In a Linux environment, permissions issues can waste you a lot of time. From now on, whenever you create some files, be sure to use chmod to set the correct permissions. Otherwise, the file may first be created by the "PHP" user, but you log in to work with other users, the system will deny access or open files, you have to struggle to get root permissions, change file permissions, and so on.
Read and write for owner, read for everybody else
chmod ("/somedir/somefile", 0644);
Everything for owner, read and execute for others
chmod ("/somedir/somefile", 0755);
15. Do not rely on submit button values to check form submission behavior
if ($_post[' submit '] = = ' Save ')
{
Save the Things
}
Most of the above is true, except that the application is multilingual. ' Save ' may represent other meanings. How do you tell them apart? Therefore, do not rely on the value of the Submit button.
if ($_server[' request_method '] = = ' POST ' and isset ($_post[' submit '))
{
Save the Things
}
Now you are freed from the value of the Submit button.
16. Define a static variable for a variable that always has the same value within a function
Delay for some time
function delay ()
{
$sync _delay = get_option (' Sync_delay ');
echo "<br/>delaying for $sync _delay seconds ...";
Sleep ($sync _delay);
echo "Done <br/>";
}
Replace with static variables:
Delay for some time
function delay ()
{
static $sync _delay = null;
if ($sync _delay = null)
{
$sync _delay = get_option (' Sync_delay ');
}
echo "<br/>delaying for $sync _delay seconds ...";
Sleep ($sync _delay);
echo "Done <br/>";
}
17. Do not use $_session variables directly
Some simple examples:
$_session[' username ' = $username;
$username = $_session[' username '];
This can cause some problems. If multiple applications are running in the same domain name, the session variable may conflict. Two different applications may use the same session key. For example, a front-end portal, and a background management system using the same domain name.
From now on, use the application-related key and a wrapper function:
Define (' app_id ', ' abc_corp_ecommerce ');
Function to get a session variable
function Session_get ($key)
{
$k = app_id. '.' . $key;
if (Isset ($_session[$k]))
{
return $_session[$k];
}
return false;
}
Function Set the session variable
function Session_set ($key, $value)
{
$k = app_id. '.' . $key;
$_session[$k] = $value;
return true;
}
18. Encapsulate a tool function into a class
If you define a lot of tool functions in a file:
function Utility_a ()
{
This function does a utility thing like string processing
}
function Utility_b ()
{
This function does nother utility thing like database processing
}
function Utility_c ()
{
This function is ...
}
The use of these functions is dispersed throughout the application. You might want to encapsulate them in a class:
Class Utility
{
public static function Utility_a ()
{
}
public static function Utility_b ()
{
}
public static function Utility_c ()
{
}
}
and call them as
$a = utility::utility_a ();
$b = Utility::utility_b ();
The obvious benefit is that if you have a function with the same name in PHP, you can avoid conflicts.
Another view is that you can maintain multiple versions of the same class in the same application without causing conflicts. This is the basic benefit of encapsulation, without it.
Bunch of Silly tips
>> use echo instead of print
>> use Str_replace instead of preg_replace unless you absolutely need
>> do not use short tag
>> simple strings replace double quotes with single quotes
Remember to use exit after >>head redirection
>> do not call functions in loops
>>isset faster than strlen.
>> formatting code in the beginning
>> do not delete loops or if-else parentheses
Do not write code like this:
if ($a = = true) $a _count++;
This is absolutely waste.
Written:
if ($a = = true)
{
$a _count++;
}
Do not attempt to omit some syntax to shorten the code. But to keep your logic short.
>> use a text editor with the highlighted syntax. Highlighting syntax can make you less wrong.
20. Using Array_map to quickly process arrays
For example, you want to trim all the elements in an array. Novice May:
foreach ($arr as $c => $v)
{
$arr [$c] = Trim ($v);
}
But using Array_map is simpler:
$arr = Array_map (' Trim ', $arr);
This applies to call trim for each element of the $arr array. Another similar function is Array_walk. Consult your documentation for more tips.
21. Validating Data with PHP filter
You must have used regular expressions to validate emails, IP addresses, and so on. Yes, everyone uses it that way. Now, we want to do a different try, called filter.
The PHP Filter extension provides a simple way to validate and check input.
22. Mandatory type checking
$amount = intval ($_get[' amount '));
$rate = (int) $_get[' rate '];
It's a good habit.
23. If necessary, use profiler such as Xdebug
If you use PHP to develop a large application, PHP takes on a lot of computing, and speed is an important indicator. Use profile to help optimize your code. can be used
Xdebug and WebGrid.
24. Handle large arrays with care
For large arrays and strings, it must be handled with care. A common error occurs when an array copy causes a memory overflow and throws fatal error of Memory size information:
$db _records_in_array_format; This is a big array holding 1000 rows from a table each has a columns, every row is atleast-bytes, so total 10 MB = 2MB
$CC = $db _records_in_array_format; 2MB more
Some_function ($CC); Another 2MB?
This is often done when you import or export a CSV file.
Do not assume that the above code will often cause the script to crash due to memory limitations. Small variables are fine, but they must be avoided when dealing with large arrays.
Make sure that it is passed by reference or stored in a class variable:
$a = Get_large_array ();
Pass_to_function (& $a);
After doing so, pass the variable reference to the function instead of the copy array. View the document.
Class A
{
function A ()
{
$this->a = Get_large_array ();
$this->pass_to_function ();
}
function Pass_to_function ()
{
Process $this->a
}
}
Unset them as soon as possible, so that the memory can be released, reduce the burden of the script.
25. Use a single database connection from beginning to end
Make sure that your scripts use a single database connection from beginning to end. Open the connection correctly at the beginning, use it until it ends, and close it at the end. Do not open the connection in the function as follows:
function Add_to_cart ()
{
$db = new Database ();
$db->query ("INSERT into cart ...");
}
function Empty_cart ()
{
$db = new Database ();
$db->query ("DELETE from cart ...");
}
Using multiple connections is a bad thing, they slow down applications because it takes time and memory to create a connection.
Specific cases use a single case pattern, such as a database connection.
26. Avoid writing SQL directly, abstract
Patiently wrote too many of the following statements:
$query = "INSERT into the users (name, email, address, phone) VALUES (' $name ', ' $email ', ' $address ', ' $phone ')";
$db->query ($query); Call to Mysqli_query ()
This is not a plan to build a strong one. It has some disadvantages:
>> manually escape values each time
>> Verify that the query is correct
>> query errors can take a long time to identify (unless you use a if-else check every time)
>> difficult to maintain complex queries
So use function encapsulation:
function Insert_record ($table _name, $data)
{
foreach ($data as $key => $value)
{
Mysqli_real_escape_string
$data [$key] = $db->mres ($value);
}
$fields = Implode (', ', Array_keys ($data));
$values = "'". Implode ("', '", Array_values ($data)). "'";
Final Query
$query = "INSERT into {$table} ($fields) VALUES ($values)";
Return $db->query ($query);
}
$data = Array (' name ' => $name, ' email ' => $email, ' address ' => $address, ' phone ' => $phone);
Insert_record (' users ', $data);
Did you see it? This makes it easier to read and expand. The Record_data function handles the escape carefully.
The biggest advantage is that the data is preprocessed into an array, and any grammatical errors are captured.
The function should be defined in a database class, and you can call it like $db->insert_record.
Check out this article to see how it's easier to work with your database.
Similarly, you can write Update,select,delete methods. Give it a try.
27. Cache the database-generated content in a static file
If all of the content is retrieved from the database, they should be cached. Once they are generated, they are saved in a temporary file. The next time the page is requested, it can be taken directly from the cache without having to check the database again.
Benefits:
>> save time for PHP to process pages and perform faster
>> fewer database queries mean less MySQL connection overhead
28. Save session in Database
There are many limitations to the file-based session strategy. Using a file-based session cannot be extended to the cluster because the session is saved on a single server. However, the database can be accessed by multiple servers, which resolves the problem.
There are additional benefits to saving session data in the database:
>> handle Username Repeat login problem. The same username cannot log in at the same time in two places.
>> can be more prepared to query online user status.
29. Avoid using global variables
>> Use Defines/constants
>> Get values using functions
>> use classes and access via $this
30. Use base label in Head
Never heard of him? Please look below:
<base href= "Http://www.domain.com/store/" >
<body>

</body>
Base tags are useful. Suppose your application is divided into subdirectories, and they all include the same navigation menu.
www.domain.com/store/home.php
www.domain.com/store/products/ipad.php
In the home page, you can write:
<a href= "home.php" >Home</a>
<a href= "products/ipad.php" >Ipad</a>
But in your ipad.php have to write:
<a href= ". /home.php ">Home</a>
<a href= "ipad.php" >Ipad</a>
Because the directory is not the same. There are so many different versions of the navigation menu to maintain, very bad AH.
Therefore, use the base label.
<base href= "Http://www.domain.com/store/" >
<body>
<a href= "home.php" >Home</a>
<a href= "products/ipad.php" >Ipad</a>
</body>
Now, the code will behave in the same directory file as the application.
31. Never set Error_reporting to 0
Turn off error reporting that is not a phase. It is important to e_fatal mistakes.
Ini_set (' display_errors ', 1);
Error_reporting (~e_warning & ~e_notice & ~e_strict);
32. Note Platform Architecture
Integers are different in length in 32-bit and 64-bit architectures. Therefore, some functions, such as strtotime, behave differently.
In a 64-bit machine, you will see the following output.
$ php-a
Interactive Shell
php > Echo strtotime ("0000-00-00 00:00:00");
-62170005200
php > Echo strtotime (' 1000-01-30 ');
-30607739600
php > Echo strtotime (' 2100-01-30 ');
4104930600
But in 32-bit machines, they will be bool (false). See here for more information.
33. Do not rely too much on set_time_limit
If you want to limit the minimum time, you can use the following script:
Set_time_limit (30);
Rest of the Code
Do you have peace of mind? Note that any external execution, such as system calls, socket operations, database operations, and so on, is not under the control of Set_time_limits.
Therefore, even if the database spends a lot of time querying, the script will not stop executing. Depending on the situation.
34. Using an extension library
Some examples:
>>mpdf--can generate PDF documents via HTML
>>phpexcel--Read and write Excel
>>phpmailer--Easy to handle sending messages that contain nearby
>>pchart--using PHP to generate reports
Use open source libraries to accomplish complex tasks, such as generating PDFs, ms-excel files, reports, and more.
35. Using the MVC framework
It's time to use an MVC framework like CodeIgniter. The MVC framework does not force you to write object-oriented code. They only separate the PHP code from the HTML.
>> clearly differentiate between PHP and HTML code. The benefits of teamwork are that designers and programmers can work together.
>> Object-oriented design functions to make it easier for you to maintain
>> built-in functions do a lot of work, you don't need to write it over and over again
>> development of large applications is necessary
>> Many suggestions, tips and hack have been implemented by the framework
36. Often look at Phpbench
Phpbench provides benchmark results for basic PHP operations that show how some of the small variations of the grammar can cause significant differences.
Check the PHP site comments, have questions to IRC questions, often read open source code, using Linux development.
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