8 methods and code examples for reading files in PHP,

I have sorted out several methods of reading files in PHP for easy reference in the future.

1.fread

string fread ( int $handle , int $length )

fread() reads up to length bytes from the file pointed to by handle. This function is called after reading up to length bytes, or when EOF is reached, or (for network streams) when a packet is available, or (after opening a user space stream) 8192 bytes have been read. Will stop reading the file, depending on which condition is encountered first.

fread() returns the read string, or FALSE if an error occurs.

Copy code The code is as follows:

$filename = "/usr/local/something.txt";
$handle = fopen($filename, "r");//When reading a binary file, you need to set the second parameter to 'rb'

//Get the file size through filesize and read the entire file into a string at once
$contents = fread($handle, filesize ($filename));
fclose($handle);
?>

If the file to be read is not a local ordinary file, but a remote file or stream file, this method cannot be used, because filesize cannot obtain the size of these files. At this time, you need to use the return value of feof() or fread() to determine whether the end of the file has been read.

For example:

Copy code The code is as follows:

$handle = fopen('http://www.baidu.com', 'r');
$content = '';
While(!feof($handle)){
$content .= fread($handle, 8080);
}
echo $content;
fclose($handle);
?>

or:

Copy code The code is as follows:

$handle = fopen('http://www.baidu.com', 'r');
$content = '';
While(false != ($a = fread($handle, 8080))){//Returning false indicates that the end of the file has been read
$content .= $a;
}
echo $content;
fclose($handle);
?>

2.fgets

string fgets ( int $handle [, int $length ] )

fgets() reads a line from the file pointed to by handle and returns a string with a length of at most length - 1 bytes. Stops when a newline character (included in the return value), EOF, or length - 1 bytes has been read (whichever occurs first). If length is not specified, it defaults to 1K, or 1024 bytes.

Copy code The code is as follows:

$handle = fopen('./file.txt', 'r');
While(!feof($handle)){
echo fgets($handle, 1024);
}
fclose($handle);
?>

Note: The length parameter is optional as of PHP 4.2.0, if omitted, the length of the line is assumed to be 1024. Starting with PHP 4.3, omitting length will continue reading from the stream until the end of the line. If most of the lines in the file are larger than 8KB, specifying the maximum line length in the script is more efficient in utilizing resources. Starting with PHP 4.3 this function is safe for use with binary files. Earlier versions don't.

3.fgetss

string fgetss ( resource $handle [, int $length [, string $allowable_tags ]] )

Same function as fgets, but fgetss will try to remove any HTML and PHP tags from the read text. You can use the optional third parameter to specify which tags are not to be removed.

Copy code The code is as follows:

$handle = fopen('./file.txt', 'r');
While(!feof($handle)){
echo fgetss($handle, 1024, '
');
}
fclose($handle);
?>

4.file

array file ( string $filename [, int $use_include_path [, resource $context ]] )

Read the file contents into an array. Each item in the array corresponds to a line in the file, including newlines. You can use the rtrim() function to filter out newline characters when line terminators are not required.

Copy code The code is as follows:

$a = file('./file.txt');
foreach($a as $line => $content){
echo 'line '.($line + 1).':'.$content;
}
?>

5.readfile

int readfile ( string $filename [, bool $use_include_path [, resource $context ]] )

Read in a file and write to the output buffer. Returns the number of bytes read from the file. Returns FALSE on error and displays an error message unless called as @readfile().

Copy code The code is as follows:

$size = readfile('./file.txt');
echo $size;
?>

6.file_get_contents

string file_get_contents ( string $filename [, bool $use_include_path [, resource $context [, int $offset [, int $maxlen ]]]] )

Read the file into a string. The third parameter $context can be used to set some parameters, such as setting timeout when accessing remote files, etc.

In addition, file_get_contents has much better performance than the above functions, so file_get_contents should be used first. But readfile seems to have better performance than file_get_contents (?), because it does not need to call fopen.

Copy code The code is as follows:

$ctx = stream_context_create(array(
'http' => array(
'timeout' => )
)
);
echo file_get_contents("http://www.baidu.com/", 0, $ctx);
?>

7.fpassthru

int fpassthru ( resource $handle )

Read the given file pointer from the current position to EOF and write the result to the output buffer.

Copy code The code is as follows:

header("Content-Type:text/html;charset=utf-8");
$handle = fopen('./test2.php', 'r');
fseek($handle, 1024);//Locate the pointer to 1024 bytes
fpassthru($handle);
?>

8.parse_ini_file

array parse_ini_file ( string $filename [, bool $process_sections ] )

parse_ini_file() loads an ini file specified by filename and returns its settings as an associative array. If you set the final process_sections parameter to TRUE, you will get a multidimensional array containing the name and settings of each section in the configuration file. The default value for process_sections is FALSE.

Note:

1. If the value in the ini file contains any non-alphanumeric characters, it needs to be enclosed in double quotes (").
2. Some reserved words cannot be used as key names in ini files, including: null, yes, no, true and false. The values null, no and false are equivalent to "", and the values yes and true are equivalent to "1". The characters {}|&~![()" also cannot be used anywhere in key names, and these characters have special meaning in option values.
test.ini file content:

Copy code The code is as follows:

; This is a sample configuration file
; Comments start with ';', as in php.ini
[first_section]

one = 1
five = 5
animal = BIRD

[second_section]

path = "/usr/local/bin"
URL = "http://www.example.com/~username

test.php content:

Copy code The code is as follows:

$config = parse_ini_file('./test.ini', ture);
Print_r($config);
?>
Output content:

Copy code The code is as follows:

Array
(
[first_section] => Array
(
[one] => 1
[five] => 5
[animal] => )
[second_section] => Array

(
[path] => [URL] => http://www.example.com/~username
)

)

A few things to note:

1. Encourage the use of the b flag when processing binary files, even if the system does not require it, so as to make the script more portable.

2. The allow_url_fopen option activates the URL form of the fopen encapsulation protocol so that URL objects such as files can be accessed. The default encapsulation protocol provides access to remote files using the ftp and http protocols. Some extension libraries such as zlib may register more encapsulation protocols. For security reasons, this option can only be set in php.ini.

3. If you want to open a URL with special characters (for example, spaces), you need to use urlencode() for URL encoding.

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