fread
(PHP 4, PHP 5, PHP 7, PHP 8)
fread — Binary-safe file read
Description
$stream, int $length): string|false
fread() reads up to
length bytes from the file pointer
referenced by stream. Reading stops as soon as one
of the following conditions is met:
-
lengthbytes have been read - EOF (end of file) is reached
- a packet becomes available or the socket timeout occurs (for network streams)
- if the stream is read buffered and it does not represent a plain file, at most one read of up to a number of bytes equal to the chunk size (usually 8192) is made; depending on the previously buffered data, the size of the returned data may be larger than the chunk size.
Parameters
-
stream -
A file system pointer resource that is typically created using fopen().
-
length -
Up to
lengthnumber of bytes read.
Return Values
Returns the read string or false on failure.
Examples
Example #1 A simple fread() example
<?php
// get contents of a file into a string
$filename = "/usr/local/something.txt";
$handle = fopen($filename, "r");
$contents = fread($handle, filesize($filename));
fclose($handle);
?>
Example #2 Binary fread() example
On systems which differentiate between binary and text files (i.e. Windows) the file must be opened with 'b' included in fopen() mode parameter.
<?php
$filename = "c:\\files\\somepic.gif";
$handle = fopen($filename, "rb");
$contents = fread($handle, filesize($filename));
fclose($handle);
?>
Example #3 Remote fread() examples
When reading from anything that is not a regular local file, such as streams returned when reading remote files or from popen() and fsockopen(), reading will stop after a packet is available. This means that you should collect the data together in chunks as shown in the examples below.
<?php
$handle = fopen("http://www.example.com/", "rb");
$contents = stream_get_contents($handle);
fclose($handle);
?>
<?php
$handle = fopen("http://www.example.com/", "rb");
if (FALSE === $handle) {
exit("Failed to open stream to URL");
}
$contents = '';
while (!feof($handle)) {
$contents .= fread($handle, 8192);
}
fclose($handle);
?>
Notes
Note:
If you just want to get the contents of a file into a string, use file_get_contents() as it has much better performance than the code above.
Note:
Note that fread() reads from the current position of the file pointer. Use ftell() to find the current position of the pointer and rewind() to rewind the pointer position.
See Also
- fwrite() - Binary-safe file write
- fopen() - Opens file or URL
- fsockopen() - Open Internet or Unix domain socket connection
- popen() - Opens process file pointer
- fgets() - Gets line from file pointer
- fgetss() - Gets line from file pointer and strip HTML tags
- fscanf() - Parses input from a file according to a format
- file() - Reads entire file into an array
- fpassthru() - Output all remaining data on a file pointer
- fseek() - Seeks on a file pointer
- ftell() - Returns the current position of the file read/write pointer
- rewind() - Rewind the position of a file pointer
- unpack() - Unpack data from binary string
