fwrite() writes the contents of string
to the file stream pointed to by handle
.
A file system pointer resource that is typically created using fopen().
The string that is to be written.
If the length
argument is given, writing will stop after length
bytes have been written or the end of string
is reached, whichever comes first.
Note that if the length
argument is given, then the magic_quotes_runtime configuration option will be ignored and no slashes will be stripped from string
.
fwrite() returns the number of bytes written, or FALSE
on error.
Writing to a network stream may end before the whole string is written. Return value of fwrite() may be checked:
<?php function fwrite_stream($fp, $string) { for ($written = 0; $written < strlen($string); $written += $fwrite) { $fwrite = fwrite($fp, substr($string, $written)); if ($fwrite === false) { return $written; } } return $written; } ?>
On systems which differentiate between binary and text files (i.e. Windows) the file must be opened with 'b' included in fopen() mode parameter.
If handle
was fopen()ed in append mode, fwrite()s are atomic (unless the size of string
exceeds the filesystem's block size, on some platforms, and as long as the file is on a local filesystem). That is, there is no need to flock() a resource before calling fwrite(); all of the data will be written without interruption.
If writing twice to the file pointer, then the data will be appended to the end of the file content:
<?php $fp = fopen('data.txt', 'w'); fwrite($fp, '1'); fwrite($fp, '23'); fclose($fp); // the content of 'data.txt' is now 123 and not 23! ?>
<?php $filename = 'test.txt'; $somecontent = "Add this to the file\n"; // Let's make sure the file exists and is writable first. if (is_writable($filename)) { // In our example we're opening $filename in append mode. // The file pointer is at the bottom of the file hence // that's where $somecontent will go when we fwrite() it. if (!$handle = fopen($filename, 'a')) { echo "Cannot open file ($filename)"; exit; } // Write $somecontent to our opened file. if (fwrite($handle, $somecontent) === FALSE) { echo "Cannot write to file ($filename)"; exit; } echo "Success, wrote ($somecontent) to file ($filename)"; fclose($handle); } else { echo "The file $filename is not writable"; } ?>
fread() -
fopen() -
popen() -
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