PHP Doku:: Ermittelt die aktuelle Position des Dateizeigers - function.ftell.html

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ftell Ermittelt die aktuelle Position des Dateizeigers


int ftell ( resource $handle )

Gibt die aktuelle Position des Dateizeigers handle zurück, z.B. seinen Offset im Dateistream.

Wenn ein Fehler auftritt, wird FALSE zurückgegeben.

Der Dateizeiger muss gültig sein und auf eine erfolgreich durch fopen() oder popen() geöffnete Datei zeigen.

Siehe auch fopen(), popen(), fseek() und rewind().

5 BenutzerBeiträge:
- Beiträge aktualisieren...
burninleo at gmx dot net
7.09.2009 22:38
When opening a file to append via fopen('file','ab') the file pointer should be at the end of the file. However ftell() returns int(0) even if the file is not empty and even after writing some text into the file.
missilesilo at gmail dot com
28.02.2007 0:02
In response to php at michielvleugel dot com:

This does not seem to be the case with PHP 5.2.0 and FreeBSD 5.4.

= ftell(STDIN);

root@localhost:/home/david# echo Hello World | ./test.php
root@localhost:/home/david# ./test.php

When something is piped to the script, it returns an integer value of 0, however, it also returns an integer when nothing is piped to the script.

The code should  be modified to this:

= ftell(STDIN);

if (
$tell === 0)
"Something was piped: " . fread(STDIN,256) . "\n";
"Nothing was piped\n";

And the result is:

root@localhost:/home/david# echo Hello World | ./test.php
Something was piped: Hello World
root@localhost:/home/david# ./test.php
Nothing was piped
mbirth at webwriters dot de
21.10.2005 20:09
Attention! If you open a file with the "text"-modifier (e.g. 'rt') and the file contains \r\n as line-endings, ftell() returns the position as if there were only \n as line-endings.

If the first line only contains 1 char followed by \r\n, the start of the second line should be position 3. (1char + \r + \n = 3 bytes) But ftell() will return 2 - ignoring one byte. If you call ftell() in line 3, the value will differ from the real value by 2 bytes. The error gets greater with every line.

(Watched this behavior in PHP 5.0.4 for Windows.)

BUT: fseek() works as expected - using the true byte values.
mweierophinney at gmail dot com
21.06.2005 19:00
Actually, ftell() gives more than an undefined result for append only streams; it gives the offset from the end of the file as defined before any data was appended. So if you open a file that had 3017 characters, and append 41 characters, and then execute ftell(), the value returned will be 41.
php at michielvleugel dot com
1.06.2005 12:19
When trying to determine whether or not something was piped into a command line script, it is not smart to do a fgets(STDIN), because it will wait indefenitely if nothing is piped. Instead, I found ftell on STDIN to be very handy: it will return an integer of zero when something was piped, and nothing if nothing was piped to the script.

#!/usr/bin/php4 -q
#following will hang if nothing is piped:
#$sometext = fgets(STDIN, 256)

$tell = ftell(STDIN);

if (
"Something was piped: ".fread(STDIN,256)."\n";}
"Nothing was piped\n";}


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