8 Developer-Required PHP features

Developers who have done PHP development should be aware that PHP has a lot of built-in features, mastered them, can help you in the development of PHP more handy, this article will share 8 development of the necessary PHP features, all very practical, I hope that you PHP developers can master.

1, pass any number of function parameters

We're in. NET or Java programming, the number of general function parameters is fixed, but PHP allows you to use any number of parameters. The following example shows you the default parameters for PHP functions:

Two default parameters function foo ($arg 1 = ", $arg 2 =") {echo "arg1: $arg 1\n"; echo "arg2: $arg 2\n";} Foo (' Hello ', ' world '); /* Output: Arg1:hello arg2:world */foo (); /* Output: arg1:arg2: */

The following example is an indeterminate parameter usage of PHP, which is used in the? Func_get_args () Method:

Yes, the formal parameter list is empty function foo () {//Gets all the array of incoming parameters $args = Func_get_args (); foreach ($args as $k = + $v) {echo "arg". $k + 1). ": $v \ n"; }}foo (); /* Nothing will output */foo (' Hello '); /* Output Arg1:hello */foo (' Hello ', ' world ', ' again '); /* Output Arg1:hello arg2:world Arg3:again */

2. Use Glob () to find files

The function names of most PHP functions are literally understandable, but when you see the Glob (), you may not know what this is for, in fact Glob () and Scandir () can be used to find files, see the following usage:

Get all the suffixes for php files $files = glob (' *.php ');p rint_r ($files); /* Output: Array ([0] = phptest.php [1] = pi.php [2] = = post_output.php [3] = test.php) */

You can also find multiple suffix names

Fetch PHP files and txt files $files = glob (' *.{ Php,txt} ', Glob_brace);p Rint_r ($files); /* Output: Array ([0] = phptest.php [1] = pi.php [2] = = post_output.php [3] = = test.php [4] = = Log.txt [5] =& Gt Test.txt) */

You can also add a path:

$files = Glob ('.. /images/a*.jpg ');p rint_r ($files); /* Output: Array ([0] = =. /images/apple.jpg [1] = =. /images/art.jpg) */

If you want an absolute path, you can call the? Realpath () function:

$files = Glob ('.. /images/a*.jpg '),//Applies the function to each array element $files = Array_map (' Realpath ', $files);p Rint_r ($files); /* Output looks like:array ([0] = C:\wamp\www\images\apple.jpg [1] = C:\wamp\www\images\art.jpg) */

3. Get Memory usage information

PHP's memory recovery mechanism is very powerful, you can also use PHP script to get the current memory usage, call the Memory_get_usage () function to get memory usage in the period, call the Memory_get_peak_usage () function to get the peak memory usage. The reference code is as follows:

echo "Initial:". Memory_get_usage (). "Bytes \ n"; /* Output initial:361400 bytes *///use memory for ($i = 0; $i < 100000; $i + +) {$array []= MD5 ($i);} Delete half of the memory for ($i = 0; $i < 100000; $i + +) {unset ($array [$i]);} echo "Final:". Memory_get_usage (). "Bytes \ n"; /* Prints final:885912 bytes */echo "Peak:". Memory_get_peak_usage (). "Bytes \ n"; /* Output Peak peak:13687072 bytes */

4. Get CPU usage information

Get memory usage, or use PHP's Getrusage () to get CPU usage, which is not available under Windows.

Print_r (Getrusage ()); /* Output Array ([Ru_oublock] = 0 [Ru_inblock] = 0 [RU_MSGSND] = 2 [RU_MSGRCV] + 3 [Ru_maxrss] = 12692 [ru  _IXRSS] = 764 [Ru_idrss] = 3864 [Ru_minflt] = 94 [Ru_majflt] = 0 [Ru_nsignals] = 1 [RU_NVCSW] + 67  [RU_NIVCSW] = 4 [Ru_nswap] = 0 [Ru_utime.tv_usec] = 0 [Ru_utime.tv_sec] = 0 [ru_stime.tv_usec] + 6269 [Ru_stime.tv_sec] = 0) */

This structure looks very obscure, unless you know the CPU well. Here are some explanations:

• Ru_oublock: Block output operation
• Ru_inblock: Block input operation
• RU_MSGSND: Message Sent
• RU_MSGRCV: Message Received
• Ru_maxrss: Maximum resident set size
• RU_IXRSS: Total Shared memory size
• Ru_idrss: Total non-shared memory size
• Ru_minflt: Page Recycling
• Ru_majflt: Page Failure
• Ru_nsignals: Received Signal
• RU_NVCSW: Active Context Switch
• RU_NIVCSW: Passive Context Switch
• Ru_nswap: Swap Area
• RU_UTIME.TV_USEC: User state time (microseconds)
• RU_UTIME.TV_SEC: User state time (seconds)
• RU_STIME.TV_USEC: System kernel Time (microseconds)
• RU_STIME.TV_SEC: System kernel time? (seconds)

To see how much CPU your script consumes, we need to look at the "user-state time" and "system kernel Time" values. Seconds and microseconds are provided separately, and you can divide the microsecond value by 1 million and add it to the second value to get the number of seconds that have fractional parts.

Sleep for 3 seconds (non-busy) sleep (3); $data = Getrusage (); echo "User time:". ($data [' ru_utime.tv_sec '] + $data [' ru_utime.tv_usec ']/1000000); echo "System time:". ($data [' ru_stime.tv_sec '] + $data [' ru_stime.tv_usec ']/1000000);/* Output User time:0.011552 System time:0 */

Sleep is not taking up the system time, we can look at one of the following examples:

Loop million times (busy) for ($i =0; $i <10000000; $i + +) {} $data = Getrusage (); echo "User time:". ($data [' ru_utime.tv_sec '] + $data [' ru_utime.tv_usec ']/1000000); echo "System time:". ($data [' ru_stime.tv_sec '] + $data [' ru_stime.tv_usec ']/1000000);/* Output User time:1.424592 System time:0.004204 */

This took about 14 seconds of CPU time, almost all of it was user time, because there was no system call.

The system time is the time that the CPU spends executing kernel instructions on the system call. Here is an example:

$start = Microtime (true); Keep calling microtime for on 3 seconds while (Microtime (True) – $start < 3) {} $data = Getrusage (); echo "User time:". ($data [' ru_utime.tv_sec '] + $data [' ru_utime.tv_usec ']/1000000); echo "System time:". ($data [' ru_stime.tv_sec '] + $data [' ru_stime.tv_usec ']/1000000);/* Prints User time:1.088171 System time:1.675315 */

We can see that the above example consumes more CPU.

5. Get System Constants

PHP provides very useful system constants that allow you to get the current line number (__line__), file (__file__), directory (__dir__), function name (__function__), class name (__class__), method name (__method__) and namespace (__namespace__), very much like C language.

We can assume that these things are mainly used for debugging, and when not necessarily, for example, can we use other files when we include them? __file__ (of course, you can also use __dir__ after PHP 5.3), here's an example.

This was relative to the loaded script ' s path//It could cause problems when running scripts from different directories R Equire_once (' config/database.php ');//This is all relative to this file's path//no matter where it was included from Require_once (DirName (__file__). '/config/database.php ');

Here is the use of __line__ to output some debug information, which will help you debug your program:

Some code//... my_debug ("Some debug message", __line__); /* Output line 4:some Debug message *///Some more code//... my_debug ("Another debug Message", __line__); /* Output line 11:another debug Message */function my_debug ($msg, $line) {echo ' line $line: $msg \ n ';}

6. Generate a unique ID

Many friends use MD5 () to generate unique numbers, but MD5 () has several drawbacks: 1, unordered, which results in degraded sorting performance in the database. 2, too long, need more storage space. In fact, PHP comes with a function to generate a unique ID, this function is Uniqid (). Here's how to use:

Generate Unique string echo uniqid (); /* Output 4bd67c947233e *///generate another unique string echo uniqid (); /* Output 4bd67c9472340 */

The algorithm is generated according to the CPU timestamp, so in a similar time period, the ID of the first few are the same, it is convenient to sort the ID, if you want to better avoid repetition, you can prefix the ID, such as:

Prefix echo uniqid (' Foo_ '); /* Output foo_4bd67d6cd8b8f *///has more entropy echo uniqid (", true); /* Output 4bd67d6cd8b926.12135106 *///all have echo uniqid (' Bar_ ', true); /* Output bar_4bd67da367b650.43684647 */

7. Serialization

PHP serialization features are probably more common, and when you need to store the data in a database or file, you can use PHP's serialize () and Unserialize () methods to achieve serialization and deserialization, the code is as follows:

A complex array of $myvar = Array (' Hello ', ' 1 ', ' array '), ' Apple ');//Serialization $string = Serialize ($myvar); Echo $string; /* Output a:4:{i:0;s:5: "Hello"; I:1;i:42;i:2;a:2:{i:0;i:1;i:1;s:3: "Both";} I:3;s:5: "Apple";} *///reverse Order $newvar = unserialize ($string);p rint_r ($newvar); /* Output Array ([0] = hello [1] = [2] = = Array ([0] = + 1 [1] = +) [3] = apple) */

How to serialize to JSON format, rest assured, PHP is ready for you, using PHP 5.2 or later users can use the Json_encode () and Json_decode () function to implement the JSON format serialization, the code is as follows:

A complex array $myvar = array (' Hello ',, Array (1, ' n '), ' Apple ');/convert to a string $string = Json_encode ($myvar) ; Echo $string; /* Prints ["Hello", 42,[1, "I"], "apple"] *///you can reproduce the original variable $newvar = Json_decode ($string);p rint _r ($newvar); /* Prints Array ([0] = hello [1] = [2] = = Array ([0] = 1 [1] +-) [3] = apple) */

8. String compression

When we talk about compression, we may think of file compression, in fact, strings can also be compressed. PHP provides the? Gzcompress ()   and  gzuncompress ()   functions:

$string = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc ut elit id mi ultricies adipiscing. Nulla Facilisi. Praesent pulvinar, sapien vel feugiat vestibulum, nulla dui pretium orci, non ultricies elit lacus quis ante. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aliquam pretium ullamcorper urna quis iaculis. Etiam ac massa sed turpis tempor luctus. Curabitur sed nibh eu elit mollis congue. Praesent ipsum diam, Consectetur vitae ornare A, aliquam a nunc. In ID magna pellentesque tellus posuere adipiscing. Sed non mi metus, at Lacinia Augue. Sed magna nisi, ornare in mollis in, mollis sed nunc. Etiam at Justo in Leo Congue mollis. Nullam in Neque eget metus hendrerit scelerisque eu non enim. Ut malesuada lacus EU nulla bibendum ID euismod urna sodales. "; $compressed = Gzcompress ($string); echo" Original size: ". Strlen ($string). " \ n "; /* Output Original size original size:800 */echo "Compressed size:". Strlen ($compressed). " \ n "; /* Output Compressed size compressed size:418 *///uncompressed $originAl = Gzuncompress ($compressed); 

There are almost 50% compression ratios. Also, you can use the Gzencode () and Gzdecode () functions to compress without using a different compression algorithm.

8 Developer-Required PHP features