php程序页面空白问题排查方法详解

<?php
 calss Math{
 const pi=3.14159;
}
echo Math::pi;
?>

＜?php
define("CONSTANT", "Hello world.");
echo CONSTANT; // outputs "Hello world."
echo Constant; // outputs "Constant" and issues a notice.
?＞

class Counter
{
public static $count = 0;//定义一个静态属性
//定义一个静态的方法
static function getCount()
{
return self::$count;
}
｝
echo Counter::getCount();
Counter::count;

<?php

echo HAHA;

class test {
    public $name2 = 'name2';
    static $name = 'name';
    const CHARSET = "中国";
    public function say_hello() {
        echo self :: CHARSET;
    }

    public static function set_name() {
        echo self :: $name;
    }

    public static function set_name2() {
        self::set_name();
    }
  
    public static function set_name3() {
        echo $this->name;
        $this->set_name();
    }
  
}
$const1 = new test();

// 1
$const1->say_hello();

// 2
echo "<br />";
echo test :: CHARSET;

// 3
echo "<br />";
echo $const1->name;

// 4
echo "<br />";
echo $const1->set_name();

// 5
echo "<br />";
echo $const1->set_name2();

// 6
echo "<br />";
echo test::CHARSET;

// 7
echo "<br />";
echo $const1->CHARSET;
?>

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://www.111cn.net");
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); //如果把这行注释掉的话，就会直接输出
$result=curl_exec($ch);
curl_close($ch);

<?php
//在类外面通常这样定义常量
define("PHP","111cn.net");
class MyClass
{
    //常量的值将始终保持不变。在定义和使用常量的时候不需要使用$符号
    const constant = 'constant value';
 
    function showConstant() {
        echo  self::constant . "<br>";
    }
}
 
echo MyClass::constant . "<br>";
 
$classname = "MyClass";
echo $classname::constant . "<br>"; // PHP 5.3.0之后
 
$class = new MyClass();
$class->showConstant();
echo $class::constant."<br>"; // PHP 5.3.0之后
//print_r(get_defined_constants());  //可以用get_defined_constants()获取所有定义的常量
?>

<?php
    //@blog<http://www.111cn.net>
    const a = "abcdef";
    echo a;
?>

<?php
const  FOO = 'PHP';
 
for ($i = 0; $i < 32; ++$i) {
    define('PHP_' . $i, 1 << $i);
}
?>

<formaction="?"method="post"enctype='multipart/form-data'>
文件上传：<inputtype="file"name="file"id="file"/>
<inputtype="submit"id="send"value="提交"/>
</form>

<script>
varsend=document.getElementById("send");
send.onclick=function(){
varfile=document.getElementById("file").value;
if(file.length<1){
alert('请选择图片');
returnfalse;
}
}
</script>

<?php
//判断pic文件框是否已经选择文件
if(!empty($_FILES['file']['tmp_name'])){
echo'已选择文件';
}else{
echo'请选择文件';
}
//PS：$_FILES后面的['tmp_name']一定不要忘写，它表示是一个临时的意思
?>

functionCheckWorkFile()
{
varobj=document.getElementById('fuMain');
if(obj.value=='')
{
alert('请选择要上传的作业书文件');
returnfalse;
}
varstuff=obj.value.match(/^(.*)(＼.)(.{1,8})$/)[3];
if(stuff!='doc')
{
alert('文件类型不正确，请选择.doc文件');
returnfalse;
}
returntrue;
}

function file_type($filename)
{
    $file = fopen($filename, "rb");
    $bin = fread($file, 2); //只读2字节
    fclose($file);
    $strInfo = @unpack("C2chars", $bin);
    $typeCode = intval($strInfo['chars1'].$strInfo['chars2']);
    $fileType = '';
    switch ($typeCode)
    {
        case 7790:
            $fileType = 'exe';
            break;
        case 7784:
            $fileType = 'midi';
            break;
        case 8297:
            $fileType = 'rar';
            break;       
  case 8075:
            $fileType = 'zip';
            break;
        case 255216:
            $fileType = 'jpg';
            break;
        case 7173:
            $fileType = 'gif';
            break;
        case 6677:
            $fileType = 'bmp';
            break;
        case 13780:
            $fileType = 'png';
            break;
        default:
            $fileType = 'unknown: '.$typeCode;
    }

 //Fix
 if ($strInfo['chars1']=='-1' AND $strInfo['chars2']=='-40' ) return 'jpg';
 if ($strInfo['chars1']=='-119' AND $strInfo['chars2']=='80' ) return 'png';

    return $fileType;
}

echo file_type('start.php');   // 6063 or 6033