A hint for PHP beginners like me:
The buffered output which is write by fflush() has nothing to do with the output buffer which is initiated by the ob_start() function.
(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)
fflush — Força a liberação do buffer para um arquivo
$stream): bool
Esta função força a escrita de toda saída cacheada para o recurso
apontado fluxo de arquivo stream.
streamO ponteiro de arquivo deve ser válido e deve apontar para um arquivo aberto com sucesso por fopen() ou fsockopen() (e ainda não fechado por fclose()).
Retorna true em caso de sucesso ou false em caso de falha.
Exemplo #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);
?>
A hint for PHP beginners like me:
The buffered output which is write by fflush() has nothing to do with the output buffer which is initiated by the ob_start() function.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.