PHP中的字节操作 [英] Byte manipulation in PHP

问题描述

在PHP中，如果您有一个带有二进制数据的变量，那么如何从数据中获取特定的字节?例如，如果我有一些30字节长的数据，如何获得前8个字节?

In PHP, if you have a variable with binary data, how do you get specific bytes from the data? For example, if I have some data that is 30 bytes long how do I get the first 8 bytes?

现在，我使用substr()函数将其视为字符串:

Right now, I'm treating it like a string, using the substr() function:

$data = //...
$first8Bytes = substr($data, 0, 8);

对二进制数据使用substr是否安全?

Is it safe to use substr with binary data?

还是我应该使用其他功能?

Or are there other functions that I should be using?

推荐答案

通常，PHP中的所有字符串函数都可以安全地与原始字节一起使用.主要出现的问题是空字节，但仅用于文件系统功能: http ://php.net/manual/zh-CN/security.filesystem.nullbytes.php

Generally all string functions in PHP are safe to use with raw bytes. The issue that mostly crops up are null-bytes, but only for filesystem-functions: http://php.net/manual/en/security.filesystem.nullbytes.php

您的substr()非常适合与二进制字符串一起使用.其他一些功能，例如strtok和ereg，却与C相连，在这里C变成了"\ 0"字符.

Your substr() is perfectly fine to use with binary strings. Some other functions like strtok and ereg however interface to C, where the "\0" character becomes an issue.

这篇关于PHP中的字节操作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！