Summary of various ways to operate files in PHP (with code)

This article introduces to you a summary of various ways to operate files in PHP (with code), which has certain reference value. , friends in need can refer to it, I hope it will be helpful to you.

Normally speaking, PHP is a perfect match for operating MySQL, but if you consider security issues or disk space issues, and the data involved is relatively small, you may consider using it. stored as files. However, it should be noted that under Ubuntu or centos, file opening often fails due to permission issues, so you need to set permissions when operating files.

1. Read the file

The normal code for reading the file is as follows

$filename = "wel.txt"; $fp = fopen($filename, "r"); $data = fread($fp, filesize($filename)); echo $data; fclose($fp);

Passed Another way to read the file

$filename = "wel.txt"; $data = file_get_contents($filename, filesize($filename)); echo $data;

Read the file line by line

$filename = "wel.txt"; $fp = fopen($filename, "rb"); while(!feof($fp)) { $line = fgets($fp); echo $line.'
'; }fclose($fp);

Other way to read

$filename = "wel.txt"; readfile($filename);

$filename = "wel.txt"; $fp = fopen($filename, "r"); fpassthru($fp);

$filename = "wel.txt"; $filearray = file($filename); print_r($filearray);

2. Write to file

$filename = "wel.txt"; $content = "xiaoD"; $fp = fopen($filename, "a"); fwrite($fp, $content, strlen($content)); fclose($fp);

3. File lock

In order to prevent When reading a file when writing a file, we often lock the file being written

$filename = "wel.txt";$content = "xiaoD"; $fp = fopen($filename, "a"); flock($fp, LOCK_EX); fwrite($fp, $content, strlen($content)); flock($fp, LOCK_UN); fclose($fp);

4. Other functions

Judge whether the file exists

$filename = "we2l.txt"; if(file_exists($filename)) { readfile($filename); } else { echo 'file not exists'; }

Delete a file

$filename = "we2l.txt"; if(file_exists($filename)) { unlink($filename); } else { echo 'file not exists'; }

Set the position of the file pointer

fseek($fp, 2);

Get the position of the file pointer

ftell($fp);

The file pointer is set at the beginning of the file

rewind($fp);

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