php中运算符使用方法总结

<?php
$a=10;
$b=5;
$c=$a++; //先赋值，后自增。$c=$a,$a=$a+1
$d=$b--; //先赋值，后自减。$d=$b,$b=$a-1
echo '$a='.$a."||".'$c='.$c.'<br/>'; //$a=11,$c=10
echo '$b='.$b."||".'$d='.$d.'<br/>'; //$b=4,$d=5
?>

<?php
$a=10;
$b=5;
$c=++$a; //先自增，后赋值。$a=$a+1，$c=$a
$d=--$b; //先自减，后赋值。$b=$a-1, $d=$b
echo '$a='.$a."||".'$c='.$c.'<br/>'; //$a=11,$c=11
echo '$b='.$b."||".'$d='.$d.'<br/>'; //$b=4,$d=4
?>

$str = $_GET['abc'] ? 'wangjinbo' : 'wjb';

$a=10;$b=7;
if($a++>8 || $b++>7){ //$a++>8为真，$b++>7这个就不执行了
echo 'OK!';
}
echo 'a='.$a.'b='.$b; // 输出OK，a=11,b=7

改变一下

$a=10;$b=7;
if($a++>10 && $b++>7){ //$a++>8为假，$b++>7这个就不执行了
echo 'OK!';
}
echo 'a='.$a.'b='.$b; // a=11,b=7

<?php
/*
 * Ignore the top section,
 * it is just formatting to make output clearer.
 */

$format = '(%1$2d = %1$04b) = (%2$2d = %2$04b)'
        . ' %3$s (%4$2d = %4$04b)' . "n";

echo <<<EOH
 ---------     ---------  -- ---------
 result        value      op test
 ---------     ---------  -- ---------
EOH;

/*
 * Here are the examples.
 */

$values = array(0, 1, 2, 4, 8);
$test = 1 + 4;

echo "n Bitwise AND n";
foreach ($values as $value) {
    $result = $value & $test;
    printf($format, $result, $value, '&', $test);
}

echo "n Bitwise Inclusive OR n";
foreach ($values as $value) {
    $result = $value | $test;
    printf($format, $result, $value, '|', $test);
}

echo "n Bitwise Exclusive OR (XOR) n";
foreach ($values as $value) {
    $result = $value ^ $test;
    printf($format, $result, $value, '^', $test);
}
?>
以上例程会输出：

 ---------     ---------  -- ---------
 result        value      op test
 ---------     ---------  -- ---------
 Bitwise AND
( 0 = 0000) = ( 0 = 0000) & ( 5 = 0101)
( 1 = 0001) = ( 1 = 0001) & ( 5 = 0101)
( 0 = 0000) = ( 2 = 0010) & ( 5 = 0101)
( 4 = 0100) = ( 4 = 0100) & ( 5 = 0101)
( 0 = 0000) = ( 8 = 1000) & ( 5 = 0101)

 Bitwise Inclusive OR
( 5 = 0101) = ( 0 = 0000) | ( 5 = 0101)
( 5 = 0101) = ( 1 = 0001) | ( 5 = 0101)
( 7 = 0111) = ( 2 = 0010) | ( 5 = 0101)
( 5 = 0101) = ( 4 = 0100) | ( 5 = 0101)
(13 = 1101) = ( 8 = 1000) | ( 5 = 0101)

 Bitwise Exclusive OR (XOR)
( 5 = 0101) = ( 0 = 0000) ^ ( 5 = 0101)
( 4 = 0100) = ( 1 = 0001) ^ ( 5 = 0101)
( 7 = 0111) = ( 2 = 0010) ^ ( 5 = 0101)
( 1 = 0001) = ( 4 = 0100) ^ ( 5 = 0101)
(13 = 1101) = ( 8 = 1000) ^ ( 5 = 0101)

<?php
var_dump(0 == "a"); // 0 == 0 -> true
var_dump("1" == "01"); // 1 == 1 -> true
var_dump("10" == "1e1"); // 10 == 10 -> true
var_dump(100 == "1e2"); // 100 == 100 -> true

switch ("a") {
case 0:
    echo "0";
    break;
case "a": // never reached because "a" is already matched with 0
    echo "a";
    break;
}
?>

<?php
$foo = True; // 赋值 TRUE to $foo
?>

// == 真值判断语句
// equality and returns a boolean
if ($action == "show_version") {
    echo "The version is 1.0";
}

// 这样写不是必须的...
if ($show_separators == TRUE) {
    echo "<hr> ";
}

// 直接写，更简单些
if ($show_separators) {
    echo "<hr> ";
} 

$foo=false;
$foo1=true;
echo "为假时输出值为:".$foo; //没有输出值
echo "<br />为真时输出值为:".$foo1; //输出1

//$a=0;
//$a=0.0;
$a="0";
var_dump((bool) 0);
echo "<br />";
var_dump((bool) array());
if($a==false){
echo "空0默认转换为false，成功！";
}else{
echo "不能转换为false";
}

<?php
unlink("test.txt");
?>

<?php
$file = "test.txt";if (!unlink($file))  {
 echo ("Error deleting $file");  }else  { 
echo ("Deleted $file");  }
?>

<?php
$file = "test.txt";
if(unlink($file))
{
  echo "文件 $file 删除成功！";
}
else
{
  echo "文件 $file 删除失败！";
}
?>
</body>
</html>

<?php

$myfile = “./test1.txt”;
if (file_exists($myfile)) {
$result=unlink ($myfile);
echo $result;
}
?>

<?php
$dirname = 'testdir';
if (rmdir( $dirname )) {
    echo "目录 $dirname 删除成功";
} else {
    echo "目录 $dirname 删除失败";
}
?>

<?php
 class People{
  private $name="li ming";
 }
 $p=new People();
 echo $p->name;
?>

<?php
 class Man{
  public $name="John"; /* 设定公共属性 */
  var $age=20;
 }
 $a=new Man();
 echo $a->name."<br>";
 echo $a->age;
?>

<?php
 class Man{
  public $name="John"; 
  var $age;
 }
 $a=new Man();
 $a->name="Tom"; /* 改变属性值 */
 $a->age=20; /* 赋予属性值 */
 echo $a->name."<br>";
 echo $a->age;
?>