Learn in detail how to operate files and directories in PHP_PHP Tutorial

一:引论

　　在任何计算机设备中,文件是都是必须的对象,而在web编程中,文件的操作一直是web程序员的头疼的地方,而,文件的操作在cms系统中这是必须的,非常有用的,我们经常遇到生成文件目录,文件(夹)编辑等操作,现在我把php中的这些函数做一详细总结并实例示范如何使用.,关于对应的函数详细介绍,请查阅php手册.此处只总结重点.和需要注意的地方.(这在php手册是没有的.)

  二:目录操作

　　首先介绍的是一个从目录读取的函数,opendir(),readdir(),closedir(),使用的时候是先打开文件句柄,而后迭代列出:

$base_dir = "filelist/";
$fso = opendir($base_dir);
echo $base_dir."

---

"        ;
while($flist=readdir($fso)){
echo $flist."
"    ;
}
closedir($fso)
?>

这是讲返回文件目录下面的文件已经目录的程序(0文件将返回false).

有时候需要知道目录的信息,可以使用dirname($path)和basename($path),分别返回路径的目录部分和文件名名称部分,可用disk_free_space($path)返回看空间空余空间.

创建命令:

mkdir($path,0777)

,0777是权限码,在非window下可用umask()函数设置.

rmdir($path)

将删除路径在$path的文件.

dir -- directory 类也是操作文件目录的重要类,有3个方法,read,rewind,close,这是一个仿面向对象的类,它先使用的是打开文件句柄,然后用指针的方式读取的.,这里看php手册:

$d = dir("/etc/php5");
echo "Handle: " . $d->handle . " ";
echo "Path: " . $d->path . " ";
while (false !== ($entry = $d->read())) {
   echo $entry." ";
}
$d->close();
?>

输出:

Handle: Resource id #2
Path: /etc/php5
.
..
apache
cgi
cli

文件的属性也非常重要,文件属性包括创建时间,最后修改时间,所有者,文件组,类型,大小等

下面我们重点谈文件操作.

三:文件操作

 ●    读文件 

首先是一个文件看能不能读取(权限问题),或者存在不,我们可以用is_readable函数获取信息.:

$file = dirlist.php;
if (is_readable($file) == false) {
die(文件不存在或者无法读取);
} else {
echo 存在;
}
?>

判断文件存在的函数还有file_exists(下面演示),但是这个显然无is_readable全面.,当一个文件存在的话可以用

$file = "filelist.php";
if (file_exists($file) == false) {
die(文件不存在);
}
$data = file_get_contents($file);
echo htmlentities($data);
?>

但是file_get_contents函数在较低版本上不支持,可以先创建文件的一个句柄,然后用指针读取全部:

        $fso = fopen($cacheFile, r);
        $data = fread($fso, filesize($cacheFile));
        fclose($fso);

还有一种方式,可以读取二进制的文件:

$data = implode(, file($file));

 ●   写文件 

和读取文件的方式一样,先看看是不是能写:

$file = dirlist.php;
if (is_writable($file) == false) {
die("我是鸡毛,我不能");
}
?>

If you can write, you can use the file_put_contents function to write:

$file = dirlist.php;
if (is_writable($file) == false) {
die(I am a chicken feather, I can’t);
}
$data = I am contemptible, I want;
file_put_contents ($file, $data);
?>

file_put_contents function is a newly introduced function in php5 (not sure it exists If so, use the function_exists function to determine first) The lower version of PHP cannot be used, you can use the following method:

$f = fopen($file, w);
fwrite($f, $data);
fclose($f);

replace it.

Sometimes you need to lock when writing a file, then write:

function cache_page($pageurl,$pagedata){
if(!$fso=fopen($pageurl,w)){
$this->warns(Cache file cannot be opened.);// trigger_error
return false;
}
if(!flock($fso,LOCK_EX)){//LOCK_NB, exclusive lock
$this->warns(Cache file cannot be locked.) ;//trigger_error
return false;
}
if(!fwrite($fso,$pagedata)){//Write byte stream, serialize to write other formats
$this-> ;warns(Unable to write to cache file.);//trigger_error
return false;
}
flock($fso,LOCK_UN);//Release lock
fclose($fso);
return true;
}

● Copy and delete files

It is very easy to delete files in php, use the unlink function to operate simply:

$file = dirlist.php;
$result = @unlink ($file);
if ($result == false) {
echo mosquito Drive away;
} else {
echo Can’t drive away;
}
?>

That’s it.

Copying files is also easy:

$file = yang.txt;
$newfile = ji.txt; # The parent folder of this file must be writable
if (file_exists($file) = = false) {
die (the demo is not online and cannot be copied);
}
$result = copy($file, $newfile);
if ($result == false) {
echo Copy memory ok;
}
?>

You can use the rename() function to rename a folder. Other operations can be achieved by combining these functions.

● Get file attributes

I will talk about a few common functions:
Get the last modification time:

$file = test.txt;
echo date(r, filemtime($file));
?>

What is returned is the unix timestamp, which is commonly used in caching technology.

Related are also getting the last access time fileatime(), filectime() when the file permissions, owner, all groups or other The time when the metadata in the inode was updated, the fileowner() function returns the file owner

$owner = posix_getpwuid(fileowner($file));

(non-window system), ileperms() obtains file permissions,

$file = dirlist.php;
$perms = substr(sprintf(%o, fileperms($file)), -4);
echo $perms;
?>

filesize() returns the file size in bytes:

//Output is similar: somefile.txt: 1024 bytes

$filename = somefile.txt;
echo $filename . : . filesize($filename ) . bytes;

?>

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http://www.bkjia.com/PHPjc/509202.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/509202.htmlTechArticle1: Introduction In any computer device, files are necessary objects, and in web programming, File operations have always been a headache for web programmers, and file operations in cms systems are...