Detailed graphic and text explanation of file operation in PHP

This article mainly introduces PHP file operations, including file reading, determining whether the file exists, modification time, etc. It has certain reference value. Interested friends can refer to the examples of this article

The specific code for PHP file operation is shared with everyone for your reference. The specific content is as follows

(1) File reading

file_get_contents( )

Example:

<?php 

// 文件部分 文件的读取

// 要求把a.txt的内容读取出来，赋值给str变量

/* file_get_contents()可以获取一个文件的内容或一个网络资源的内容

file_get_contents()是读取文件/读网络数据比较快捷的一个函数，帮我们封装了打开/关闭等操作

但是要小心，这个函数一次性把文件的内容读取出来，放内存里，因此工作中处理上百M的大文件，谨慎使用
*/

$file = &#39;a.txt&#39;;
$str = file_get_contents($file);
echo $str;

/*
$url = &#39;http://www.163.com/&#39;;
$str = file_get_contents($url);
file_put_contents(&#39;162.html&#39;, $str);
*/
// 读出来的内容，能否写入另一个文件里面
/*
file_put_contents() 这个函数用来把内容写入文件
也是一个快捷函数，帮我们封装打开写入关闭的细节

注：如果指定的文件不存在，则会自动创建
*/
file_put_contents(&#39;./b.txt&#39;, $str);


/*
最简单的爬网页程序
*/
$url = &#39;http://www.sina.com/&#39;;
$html = file_get_contents($url);

if (file_put_contents(&#39;sina.html&#39;, $html)) {
 echo "抓过来了";
}else{
 echo "抓错了";
}

(2) File operation

fopen: open
fread: read
fwrite: Write
fclose: Close

Instance:

<?php

/*
 文件操作之
 fopen
 fread
 fwrite
 fclose
*/


/*
fopen() 打开一个文件，返回一个句柄资源
fopen($filename,mode);
第二个参数是‘模式&#39;，如只读模式，读写模式等
返回值：资源
*/

$file = &#39;./162.html&#39;;
$fh = fopen($file,&#39;r&#39;);

// 沿着上面返回的$file这个资源通道来读文件
echo fread($fh,10),&#39;<br />&#39;;

// 返回 int(0),说明没有成功写入
// 原因：在于第二个mode参数，选的r，即只读打开
var_dump(fwrite($fh, &#39;测试一下，能不能用&#39;));

// 关闭资源
fclose($fh);


/*
r+读写模式，并把指针指向文件头
写入成功
注：从文件头，写入时，覆盖相等字节的字符
*/
$fh = fopen($file, &#39;r+&#39;);
echo fwrite($fh, &#39;hello&#39;) ? &#39;success&#39;: &#39;fail&#39;,&#39;<br />&#39;;
fclose($fh);


/*
w:写入模式(fread读不了)
并把文件大小截为0
指针停于开头处
*/
echo &#39;<br />&#39;;
$fh = fopen(&#39;./test.txt&#39;, &#39;w&#39;);
fclose($fh);
echo "ok!";

(3) Whether the file exists and is modified Time

filemtime

<?php

/*
判断文件是否存在
获取文件的创建时间/修改时间
*/ 

$file = &#39;./students.txt&#39;;
if (file_exists($file)) {
 echo $file,"存在 <br />";
 echo &#39;上次修改时间是：&#39;,date(&#39;Y-m-d,H:i:s&#39;,filemtime($file));
}else{
 echo "不存在";
}

Demo address: Demo6-file operation

The above is the entire content of this article, I hope it will be helpful to everyone's study.

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