CascadiaPHP 2024


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

SplFileObject::ftruncateTruncates the file to a given length


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

Truncates the file to size bytes.



The size to truncate to.


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.


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


Beispiel #1 SplFileObject::ftruncate() example

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

// Truncate to 5 bytes

// Rewind and read data

Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:


Siehe auch

  • ftruncate() - Kürzt eine Datei auf die angegebene Länge

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User Contributed Notes 1 note

irvinezega at hotmail dot com
5 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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