SplFileObject::ftruncate

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

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

Опис

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

Truncates the file to size bytes.

Параметри

size: The size to truncate to.

Зауваження:
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.

Значення, що повертаються

Повертає true у разі успіху або false в разі помилки.

Приклади

Приклад #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();
?>

Поданий вище приклад виведе щось схоже на:

Hello

Прогляньте також

ftruncate() - Truncates a file to a given length

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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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