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:

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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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