php技巧篇：高质量php代码的50个实用技巧（上）

require_once('../../lib/some_class.php');

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 define('ROOT' , '/var/www/project/');
 require_once(ROOT . '../../lib/some_class.php');
 //rest of the code

//suppose your script is /var/www/project/index.php
 //Then __FILE__ will always have that full path.
 define('ROOT' , pathinfo(__FILE__, PATHINFO_DIRNAME));
 require_once(ROOT . '../../lib/some_class.php');
 //rest of the code

require_once('lib/Database.php');
 require_once('lib/Mail.php');
 require_once('helpers/utitlity_functions.php');

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');

function load_class($class_name)
 {
 //path to the class file
 $path = ROOT . '/lib/' . $class_name . '.php');
 if(file_exists($path))
 {
 require_once( $path );
 }
 }

define('ENVIRONMENT' , 'development');
 if(! $db->query( $query )
 {
 if(ENVIRONMENT == 'development')
 {
 echo "$query failed";
 }
 else
 {
 echo "Database error. Please contact administrator";
 }
 }

define('ENVIRONMENT' , 'production');
 if(! $db->query( $query )
 {
 if(ENVIRONMENT == 'development')
 {
 echo "$query failed";
 }
 else
 {
 echo "Database error. Please contact administrator";
 }
 }

/**
 Method to 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');

function add_to_cart($item_id , $qty)
  
{
 $_SESSION['cart']['item_id'] = $qty;
 }
add_to_cart( 'IPHONE3' , 2 );

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) );

<?php
 echo "Hello";
 //Now dont close this tag

 //super extra character after the closing tag
index.php

require_once('super_class.php');
 //echo an image or pdf , or set the cookies or session data

<?php
 class super_class
 {
 function super_function()
 {
 //super code
 }
 }
 //No closing tag

function print_header()
 {
 echo "Site Log and Login links";
 }
 function print_footer()
 {
 echo "Site was made by me";
 }
 print_header();
 for($i = 0 ; $i < 100; $i++)
 {
 echo "I is : $i &#39;;
 }
print_footer();

function print_header()
 {
 $o = "Site Log and Login links";
 return $o;
 }
function print_footer()
 {
 $o = "Site was made by me";
 return $o;
 }
echo print_header();
 for($i = 0 ; $i < 100; $i++)
 {
 echo "I is : $i &#39;;
 }
 echo print_footer();

$xml = '';
 $xml = "0
 ";
//Send xml data
 echo $xml;

$xml = '';
 $xml = "0
 ";
 //Send xml data
 header("content-type: text/xml");
 echo $xml;

JavaScript
header("content-type: application/x-javascript");
 echo "var a = 10";
 CSS
header("content-type: text/css");
 echo "#p id { background:#000; }";

//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: ". mysqli_connect_error());
 }
 //Set the character set of the connection
if(!mysqli_set_charset ( $c , 'UTF8' ))
 {
 die('mysqli_set_charset() failed');
 }

$value = htmlentities($this->value , ENT_QUOTES , CHARSET);

$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' ,];
  
更聪明的做法, 使用 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"]

$contents = "All the content";
$file_path = "/var/www/project/content.txt";
 file_put_contents($file_path , $contents);

$contents = "All the 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 not writable, or does not exist. Please check");
 }

// 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);

if($_POST['submit'] == 'Save')
 {
 //Save the things
 }

if( $_SERVER['REQUEST_METHOD'] == 'POST' and isset($_POST['submit']) )
 {
 //Save the things
 }

//Delay for some time
 function delay()
 {
 $sync_delay = get_option('sync_delay');
 echo "Delaying for $sync_delay seconds...";
 sleep($sync_delay);
 echo "Done ";
 }

//Delay for some time
 function delay()
 {
 static $sync_delay = null;
 if($sync_delay == null)
 {
 $sync_delay = get_option('sync_delay');
 }
 echo "Delaying for $sync_delay seconds...";
 sleep($sync_delay);
 echo "Done ";
 }

$_SESSION['username'] = $username;
 $username = $_SESSION['username'];

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;
 }

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 ...
 }

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();

if($a == true) $a_count++;

if($a == true)
 {
 $a_count++;
 }

foreach($arr as $c => $v)
 {
 $arr[$c] = trim($v);
 }

$arr = array_map('trim' , $arr);

$amount = intval( $_GET['amount'] );
$rate = (int) $_GET['rate'];

$db_records_in_array_format; //This is a big array holding 1000 rows from a table each having 20 columns , every row is atleast 100 bytes , so total 1000 * 20 * 100 = 2MB
$cc = $db_records_in_array_format; //2MB more
some_function($cc); //Another 2MB ?

$a = get_large_array();
 pass_to_function(&$a);

class A
 {
 function first()
 {
 $this->a = get_large_array();
 $this->pass_to_function();
 }
 function pass_to_function()
 {
 //process $this->a
 }
 }

function add_to_cart()
 {
$db = new Database();
 $db->query("INSERT INTO cart .....");
 }
 function empty_cart()
 {
$db = new Database();
 $db->query("DELETE FROM cart .....");
 }