PHP uses fopen function to create and open files, detailed explanation and example code

There is no separate file creation function in php. If we want to create a function, we can use fopen(). The fopen() function literally means to open a file, but this function also has the function of creating a file. When using the fopen() function to open a file , if the file does not exist, an attempt will be made to create the file and a resource will be returned.

php fopen function introduction

fopen function opens a file or URL

Syntax:

resource fopen( string filename, string mode)

fopen() binds the name resource specified by filename to a stream.

Parameters:

1. filename is the name of the file you are trying to open/create.

If filename is in the format of "scheme://...", it is treated as a URL and PHP will search for a protocol handler (also called a wrapper protocol) to handle this pattern. If the wrapper protocol has not been registered for the protocol, PHP will emit a message to help check for potential problems in the script and continue execution of filename as if it were a normal filename.

If PHP thinks filename specifies a local file, it will try to open a stream on that file. The file must be accessible to PHP, so you need to confirm that the file access permissions allow this access. If safe mode or open_basedir is activated further restrictions apply.

If PHP thinks that filename specifies a registered protocol, and the protocol is registered as a network URL, PHP will check and confirm that allow_url_fopen has been activated. If it is closed, PHP will issue a warning and the call to fopen will fail.

2. mode specifies the opening mode, and its possible values ​​are as follows:

php fopen function example

1. Use the fopen function to create a file:

$my_file = 'file.txt';//如果文件不存在（默认为当前目录下）
$handle = fopen($my_file, 'w') or die('Cannot open file: '.$my_file); //implicitly creates file

2. Use the fopen function to open a file:

$my_file = 'file.txt';//假设文件file.txt存在
$handle = fopen($my_file, 'w') or die('Cannot open file: '.$my_file); //open file for writing ('w','r','a')...

3. The fopen function is combined with fread to read the file:

$my_file = 'file.txt';
$handle = fopen($my_file, 'r');
$data = fread($handle,filesize($my_file));

4. The fopen function is combined with the fwrite function to write the file

$my_file = 'file.txt';
$handle = fopen($my_file, 'w') or die('Cannot open file: '.$my_file);
$data = 'This is the data';
fwrite($handle, $data);

5. The fopen function is combined with the fwrite function in file Additional content:

$my_file = 'file.txt';
$handle = fopen($my_file, 'a') or die('Cannot open file: '.$my_file);
$data = 'New data line 1';
fwrite($handle, $data);
$new_data = "\n".'New data line 2';
fwrite($handle, $new_data);

6. The fopen() function can also be used to open a URL on the Internet. Address:

<?php
$fh = fopen("http://www.baidu.com/", "r");
if($fh){
  while(!feof($fh)) {
    echo fgets($fh);
  }
}
?>

Note: fopen() returns only a resource. To display the opened page The address also needs to be read and output using the fgets() function.

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For more detailed explanations and example codes of using the fopen function to create and open files in PHP, please pay attention to the PHP Chinese website!