PHP fwrite function

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fwrite

(PHP 3, PHP 4, PHP 5)

fwrite() writes the contents of
string to the file stream pointed to by
handle. 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.

fwrite() returns the number of bytes
written, or FALSE on error.

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.

Note:
On systems which differentiate between binary and text files
(i.e. Windows) the file must be opened with ‘b’ included in
fopen() mode parameter.

Note:
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.

Example 1. A simple fwrite() example

$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";
}

See also fread(),
fopen(),
fsockopen(),
popen(), and
file_put_contents().