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このドキュメントでは、 php中国語ネットマニュアル リリース
(PHP 4 >= 4.0.1, PHP 5, PHP 7)
fflush — 将缓冲内容输出到文件
$handle
)
本函数强制将所有缓冲的输出写入
handle
文件句柄所指向的资源。
成功时返回 TRUE
, 或者在失败时返回 FALSE
。
文件指针必须是有效的,必须指向由 fopen() 或 fsockopen() 成功打开的文件(并还未由 fclose() 关闭)。
handle
文件指针必须是有效的,必须指向由 fopen() 或 fsockopen() 成功打开的文件(并还未由 fclose() 关闭)。
成功时返回 TRUE
, 或者在失败时返回 FALSE
。
Example #1 File write example using fflush()
<?php
$filename = 'bar.txt' ;
$file = fopen ( $filename , 'r+' );
rewind ( $file );
fwrite ( $file , 'Foo' );
fflush ( $file );
ftruncate ( $file , ftell ( $file ));
fclose ( $file );
?>
[#1] oryan at zareste dot com [2005-10-30 16:48:21]
Just a note that fflush takes care of the cache already, at least on my server. Using clearstatcache before reading a previously written file also worked, but lagged the output time much more noticeably (by two or three seconds), probably due to excess cache erasing beyond files.
[#2] jzho327 at cse dot unsw dot edu dot au [2003-01-27 00:27:37]
Sorry, the note I previously added regarding fflush() has a bug!
when you read file by calling
$fp = fopen("myfile", "a+");
and you wish to read the content, you have to call
rewind($fp) before you attemp to read it. (Silly me) Or else if you tried something like
$fp = fopen("myfile", "a+");
$content = fread($fp);
// show that content is in fact null
if ($content == NULL)
print "but it must be first put to rewind<br>\n";
will result
but it must be first put to rewind.
[new line]
in fact, if you are not careful (like me), and you opened it with
$fp = fopen("myfile", "r+");
$content = fread($fp);
..
// do something with content
..
then you tried to again
$content = fread($fp);
without rewind, you'd get NULL again. This sounds trivial, but if you work with several file resources, with freads and fopens everywhere, you can get easily lost. So becareful.