php中echo(),print(),print_r()用法

$name=print "nihao n";
$str = 'test print value is'.$name;
eval("$print="$str";");
echo $print;

if (!print("Hello, World")){

   die("you are not listening to me");

}

$str = "Hello";

$number = 123;

printf("%s world. Day number %u",$str,$number);

?>
#Results======
Hello world. Day number 123

$number = 123;

printf("With 2 decimals: %1$.2fbr />With no decimals: %1$u",$number);

?>
#Result
With 2 decimals: 123.00
With no decimals: 123

$a = array('name' => 'Fred', 'age' => '15', 'wife' => 'Wilma');

print_r($a);
Output： Array

{

   [name] => Fred

    [age] => 15

    [wife] => Wilma

}

class P {

  var $name = 'nat';

  // ...

}

$p = new P;

print_r($p);
Output: Object

{

[name] => nat

}

<?php
$str="<a href="xxx">超级链接</a>|<a href="xxx">这是个链接</a><br>";
function removelink($str){
$mode=array("#<a href="(.*)">#iUs","#</a>#iUs");
$want=array("","");
$con=preg_replace($mode,$want,$str);
return $con;
}
echo removelink($str);
?>

 Array ( [name] => hiro [city] => Shanghai [code] => 200051 [age] => 23 )

 $person = array(
 array("hiro", "23", "suzhou"),
 array("yoyo", "25", "shanghai"),
 array("janstar", "28", "xinjiang")
);
print_r()输出的原始数组结果为：

1
 Array ( [0] => Array ( [0] => hiro [1] => 23 [2] => suzhou ) [1] => Array ( [0] => yoyo [1] => 25 [2] => shanghai ) [2] => Array ( [0] => janstar [1] => 28 [2] => xinjiang ) )

function compare0($x, $y) {
 if($x[0] == $t[0]) {
  return 0;
 } elseif ($x[0] < $y[0]) {
  return -1;
 } else {
  return 1;
 }
}
 
usort($person, compare0);
echo "按第一个元素正向排序：";
print_r($person);
输出的结果如下：

1
 按第一个元素正向排序：Array ( [0] => Array ( [0] => hiro [1] => 23 [2] => suzhou ) [1] => Array ( [0] => janstar [1] => 28 [2] => xinjiang ) [2] => Array ( [0] => yoyo [1] => 25 [2] => shanghai ) )

function compare2($x, $y) {
 if($x[2] == $t[2]) {
  return 0;
 } elseif ($x[2] < $y[2]) {
  return -1;
 } else {
  return 1;
 }
}
 
usort($person, compare2);
echo "按第三个元素正向排序：";
print_r($person);
输出的结果如下：

 按第三个元素正向排序：Array ( [0] => Array ( [0] => yoyo [1] => 25 [2] => shanghai ) [1] => Array ( [0] => hiro [1] => 23 [2] => suzhou ) [2] => Array ( [0] => janstar [1] => 28 [2] => xinjiang ) )

<?php
error_reporting(0);

/**
* @数字数组排序 可按从大到小或从小到大排序 
*/
function sortArray($array, $choice) {
    $values = array_values($array); // 建立一个数字索引的数组
    $ch = $choice==0 ? min:max; // 参数$choice为0按从小到大排列，否则其他都默认为按从大到小
    do {
        $val = $ch($values); // 找出最大或最小值
        $key = array_search($val,$values); // 取得最大值的键名
        $result[$key] = $val; // 将最大值存入新数组
        unset($values[$key]);
    } while (count($values) > 0);
    return $result;
}

$array = array(100, 1000, 1, 10000);
//$array = sortArray($array, 0);
$array = sortArray($array, 1);
foreach($array as $a) {
    echo "$a ";
}
?>

function create_random_ids( $min,$max,$limited )
{
    $_base_ids = range($min,$max);
    $_temp_key = array_rand ($_base_ids,min(count($_base_ids),$limited+10));
    //拼接
    $ids = array();
    for ($x=0; $x < count($_temp_key); $x++) {
        $ids[] = $_base_ids[$_temp_key[$x]];
    }
    return $ids;
}

<?php
$a = array(0,1,2,3,4,5,6,7,8);
echo "$a原来的顺序为：<hr/>";
foreach($a as $v)
 echo $v."t";
shuffle($a);
echo "<br/>$a被打乱后的顺序为：<hr/>";
foreach($a as $v)
 echo $v."t";
?>

<?php
function Test()
{
static $a = 0;
echo $a;
$a++;
}
?> 
 

<?php
function Test()
{
static $count = 0;

$count++;
echo $count;
if ($count < 10) {
Test ();
}
$count--;
}
?>

<?php
function foo(){
static $int = 0; // correct
static $int = 1+2; // wrong  (as it is an expression)
static $int = sqrt(121); // wrong  (as it is an expression too)

$int++;
echo $int;
}
?>

 
<?php
class Fruit {
 public static $category = "I'm fruit";
   
    static function find($class)
 {
     $vars = get_class_vars($class) ;
       echo $vars['category'] ;
    }
}

class Apple extends Fruit {
     public static $category = "I'm Apple";
}

Apple::find("Apple");
?>

程序运行结果：

1 I'm Apple

 
<?php
class Fruit
{
 static function Foo ( $class = __CLASS__ )
    {
        call_user_func(array($class, 'Color'));
    }
}

class Apple extends Fruit
{
    static function Foo ( $class = __CLASS__ )
    {
        parent::Foo($class);
    }

    static function Color()
    {
        echo "Apple's color is red";
    }
}

Apple::Foo(); // This time it works.
?>

程序运行结果：

Apple's color is red

<?php
class Fruit
{
   static $color = array('color1' => 'red', 'color2' => 'yellow');
}

class Apple
{
   public function __construct()
   {
     var_dump(Fruit::$color);
   }
}

class Banana
{
  public function __construct()
  {
    Fruit::$color = FALSE;
  }
}

new Apple();    // prints array(2) { ["color1"]=> string(3) "red" ["color2"]=> string(6) "yellow" }
echo '<br />';
new Banana();
new Apple();    // prints bool(false)
?>

   
<?php
class Singleton {

    private static $instance=null;
    private $value=null;

    private function __construct($value) {
        $this->value = $value;
    }

    public static function getInstance() {
        if ( self::$instance == null ) {
            echo "<br>new<br>";
            self::$instance = new Singleton("values");
        } 
  else {
            echo "<br>old<br>";
        }
        return self::$instance;
    }

}

$x = Singleton::getInstance();
var_dump($x); // returns the new object
$y = Singleton::getInstance();
var_dump($y); // returns the existing object
?>

class A {
 static $i = 10;
 public function set($n)
 {
  self::$i = $n;
 }
 public function get()
 {
  return self::$i;
 }
}
$a = new A();
$a->set(11);
$a1= new A();
echo $a1->get();

public static void main(String[] args)
{
}