shmop_write

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

shmop_write — Write data into shared memory block

Description

shmop_write(Shmop $shmop, string $data, int $offset): int

shmop_write() will write a string into shared memory block.

Parameters

shmop: The shared memory block identifier created by shmop_open()
data: A string to write into shared memory block
offset: Specifies where to start writing data inside the shared memory segment. The offset must be greater than or equal to zero and less than or equal to the actual size of the shared memory segment.

Return Values

The size of the written data.

Errors/Exceptions

If offset is out of range, or a read-only shared memory segment should be written to, a ValueError is thrown.

Changelog

Version	Description
8.0.0	Prior to PHP 8.0.0, `false` was returned on failure.
8.0.0	`shmop` expects a Shmop instance now; previously, a resource was expected.

Examples

Example #1 Writing to shared memory block

<?php
$shm_bytes_written = shmop_write($shm_id, $my_string, 0);
?>

This example will write data inside $my_string into shared memory block, $shm_bytes_written will contain the number of bytes written.

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User Contributed Notes 2 notes

down

mark at manngo dot net ¶

1 year ago

On thing you might want to do is replace an old string with a shorter one, or to clear out the string altogether.

To replace the string, you can zero-byte pad the string you are writing:

<?php
    //    $shmid is from shmop_open()
    $size = 128;
    $string = 'something';

    //    write
        $string = str_pad(string, $size, "\0");
        shmop_write($shmid, $string, 0);

    //    read
        print rtrim(shmop($shmid,0,0),,"\0");

    //    clear
        $string = str_repeat("\0",$size);
        shmop_write($shmid, $string, 0);
?>