SplFileObject::ftruncate

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

SplFileObject::ftruncate — Truncates the file to a given length

Beschreibung

public SplFileObject::ftruncate(int $size): bool

Truncates the file to size bytes.

Parameter-Liste

size: The size to truncate to.

Hinweis:
If size is larger than the file it is extended with null bytes.

If size is smaller than the file, the extra data will be lost.

Rückgabewerte

Gibt bei Erfolg true zurück. Bei einem Fehler wird false zurückgegeben.

Beispiele

Beispiel #1 SplFileObject::ftruncate() example

<?php
// Create file containing "Hello World!"
$file = new SplFileObject("/tmp/ftruncate", "w+");
$file->fwrite("Hello World!");

// Truncate to 5 bytes
$file->ftruncate(5);

// Rewind and read data
$file->rewind();
echo $file->fgets();
?>

Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:

Hello

Siehe auch

ftruncate() - Kürzt eine Datei auf die angegebene Länge

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User Contributed Notes 1 note

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irvinezega at hotmail dot com ¶

6 years ago

I suppose a fair number of us know this: 

However, for those who don't:- 

If you are truncating a file, say, to $fileObject->ftruncate(0), then, it may be advisable to call $fileObject->fseek(0) first (before you call '$fileObject->ftruncate'). 

On inspection, I was encountering 'NULL' characters at the beginning of a, or the, file. 

Hence, from what I have surmised; when 'ftruncate()' is called, the file pointer does NOT move to the beginning (or, at least, the required position) of the file.

This issue cost me a fair amount of time to figure out, so I hope it helps someone.

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