注释

注意:

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;
}
?>

注意:

在区分二进制文件和文本文件的系统上（如 Windows） 打开文件时，fopen() 函数的 mode 参数要加上 'b'。

注意:

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.

注意:

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!
?>