Nine useful PHP Functions

1. Any number of parameters of the Function

You may know that PHP allows you to define a default parameter function. But you may not know that PHP also allows you to define a function with all arbitrary parameters.

The following example shows the default parameter functions:

// Functions with two default parameters Function foo ($ arg1 =, $ arg2 = ){ Echo "arg1: $ arg1 "; Echo "arg2: $ arg2 "; } Foo (hello, world ); /* Output: Arg1: hello Arg2: world */ Foo (); /* Output: Arg1: Arg2: */

Now let's take a look at a function with an indefinite parameter. is it used? Func_get_args () method:

// Yes, the parameter list is empty Function foo (){ // Obtain the array of all input parameters $ Args = func_get_args (); Foreach ($ args as $ k =>v v ){ Echo "arg". ($ k + 1). ": $ v "; } } Foo (); /* Nothing will be output */ Foo (hello ); /* Output Arg1: hello */ Foo (hello, world, again ); /* Output Arg1: hello Arg2: world Arg3: again */

2. Use Glob () to find files

Many PHP functions have a long self-explanatory function name? During glob (), you may not know what this function is for, unless you are familiar with it.

Do you think this function is good? Like scandir (), scandir can be used to find files.

// Obtain all files 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 extension names

// Retrieve the PHP 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 the following path: $ Files = glob (../images/a *. jpg ); Print_r ($ files ); /* Output: Array ( [0] => ../images/apple.jpg [1] => ../images/art.jpg ) */

If you want to obtain the absolute path, can you call it? Realpath () function:

$ 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: wampwwwimagesapple.jpg [1] => C: wampwwwimagesart.jpg ) */

3. memory usage information

Observe that the memory usage of your program allows you to better optimize your code.

PHP has a garbage collection mechanism and a complicated memory management mechanism. You can know the memory usage of your script. Do you want to know the current memory usage? Memory_get_usage () function. If you want to know the peak memory usage, you can call the memory_get_peak_usage () function.

Echo "Initial:". memory_get_usage (). "bytes "; /* Output Initialize: 361400 bytes */ // Memory usage For ($ I = 0; I I <100000; $ I ++ ){ $ Array [] = md5 ($ I ); } // Delete half of the memory For ($ I = 0; I I <100000; $ I ++ ){ Unset ($ array [$ I]); } Echo "Final:". memory_get_usage (). "bytes "; /* Prints Final: 885912 bytes */ Echo "Peak:". memory_get_peak_usage (). "bytes "; /* Output peak value Peak: 13687072 bytes */

4. CPU usage information

Use? The getrusage () function allows you to know the CPU usage. Note that this function is not available in Windows.

Print_r (getrusage ()); /* Output Array ( [Ru_oublock] => 0 [Ru_inblock] => 0 [Ru_msgsnd] => 2 [Ru_msgrcv] => 3 [Ru_maxrss] = & gt; 12692 [Ru_ixrss] = & gt; 764 [Ru_idrss] = & gt; 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] = & gt; 6269 [Ru_stime. TV _sec] => 0 ) */

This structure seems obscure unless you know the CPU. The following are some explanations:

Ru_oublock: block output operation Ru_inblock: block input operation Ru_msgsnd: sent message Ru_msgrcv: Received message Ru_maxrss: the largest and smallest resident set Ru_ixrss: All shared memory size Ru_idrss: all non-shared memory sizes Ru_minflt: Page recycling Ru_majflt: the page is invalid. Ru_nsignals: Received Signal Ru_nvcsw: Active context switching Ru_nivcsw: passive context switching Ru_nswap: swap Zone 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)