8 Essential PHP Feature Instance code _php tutorial

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
2. Use Glob () to find files
3. Get Memory usage information
4. Get CPU usage information
5. Get System Constants
6. Generate a unique ID
7. Serialization
8. String compression

1, pass any number of function parameters we are 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:
Copy the Code code as follows:
Two functions with 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 that uses the Func_get_args () method:
Yes, the formal parameter list is empty
function foo () {
Gets the array of all incoming arguments
$args = Func_get_args ();
foreach ($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, using Glob () Find files Most of the functions of PHP function name can literally understand its purpose, but when you see Glob (), you may not know what this is to do, in fact glob () and Scandir (), can be used to find files, see the following usage:
Copy CodeThe code is as follows:
Get all the files that are suffixed with PHP
$files = Glob (' *.php ');
Print_r ($files);
/* Output:
Array
(
[0] = phptest.php
[1] = pi.php
[2] = post_output.php
[3] = test.php
)
*/

You can also find multiple suffix names:
Copy CodeThe code is as follows:
Fetch PHP files and txt files
$files = Glob (' *.{ Php,txt} ', glob_brace);
Print_r ($files);
/* Output:
Array
(
[0] = phptest.php
[1] = pi.php
[2] = post_output.php
[3] = test.php
[4] = Log.txt
[5] = Test.txt
)
*/

You can also add a path:
Copy CodeThe code is as follows:
$files = Glob ('.. /images/a*.jpg ');
Print_r ($files);
/* Output:
Array
(
[0] = =. /images/apple.jpg
[1] = =. /images/art.jpg
)
*/

If you want an absolute path, you can call the Realpath () function:
Copy CodeThe code is as follows:
$files = Glob ('.. /images/a*.jpg ');
Applies the function to each array element
$files = Array_map (' Realpath ', $files);
Print_r ($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 recycling mechanism is very powerful, you can also use PHP script to get the current memory usage, call Memory_get_usage () function to get memory usage of the period, call Memory_get_peak_usage () function to get the peak memory usage. The reference code is as follows:
Copy the Code code as follows:
echo "Initial:". Memory_get_usage (). "Bytes \ n";
/* Output
initial:361400 bytes
*/
Using 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, can also use PHP getrusage () to get CPU usage, this method is not available under Windows.
Copy CodeThe code is as follows:
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: Sent message RU_MSGRCV: Received message Ru_maxrss: Maximum resident set size Ru_ixrss: All in Shared Storage size RU_IDRSS: Total non-shared memory size Ru_minflt: Page Recycle Ru_majflt: Page invalidation 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.
Copy CodeThe code is as follows:
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
*/

is not taking up the system time, we can look at one of the following examples:
Copy CodeThe code is as follows:
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. Traditional time is the time that the CPU spends executing kernel instructions on the system call. Here is an example:
Copy CodeThe code is as follows:
$start = Microtime (true);
Keep calling microtime for about 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
*/

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__), much like the 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.
Copy CodeThe code is as follows:
This was relative to the loaded script ' s path
It may cause problems if running scripts from different directories
Require_once (' config/database.php ');
This is all relative to the this file ' s path
No matter where it is 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:
Copy CodeThe code is as follows:
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, resulting 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:
Copy the Code code as follows:
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:
Copy the Code code as follows:
Prefix
echo uniqid (' Foo_ ');
/* Output
foo_4bd67d6cd8b8f
*/
There's more entropy.
Echo Uniqid (", true);
/* Output
4bd67d6cd8b926.12135106
*/
All have
echo uniqid (' Bar_ ', true);
/* Output
bar_4bd67da367b650.43684647
*/

7, serialized PHP serialization function You may use more, also more common, when you need to save the data to the database or file is, you can use PHP serialize () and Unserialize () method to achieve serialization and deserialization, the code is as follows:
Copy CodeThe code is as follows:
A complex array
$myvar = Array (
' Hello ',
42,
Array (1, ' both '),
' Apple '
);
Serialization of
$string = serialize ($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";}
*/
Inverse order of the case
$newvar = Unserialize ($string);
Print_r ($newvar);
/* Output
Array
(
[0] = = Hello
[1] = 42
[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:
Copy CodeThe code is as follows:
A complex array
$myvar = Array (
' Hello ',
42,
Array (1, ' both '),
' 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);
Print_r ($newvar);
/* Prints
Array
(
[0] = = Hello
[1] = 42
[2] = = Array
(
[0] = 1
[1] =
)
[3] = Apple
)
*/

8, string compression when we talk about compression, we may think of file compression, in fact, the string can also be compressed. PHP provides the gzcompress () and Gzuncompress () functions:
Copy CodeThe code is as follows:
$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 ";
/* Size after output is compressed
Compressed size:418
*/
Unzip
$original = gzuncompress ($compressed);

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

The above is the 8 development of the necessary PHP features, is not all very practical?

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