How to convert php string to bytes

PHP is an open source server-side scripting language used in web development, command line scripting and other fields. Converting between strings and bytes is a very common operation in PHP. This article will introduce how to convert strings to bytes and bytes to strings in PHP.

1. Convert strings into bytes

In PHP, you can use the pack() function to convert strings into bytes.

The syntax of the pack() function is as follows:

string pack ( string $format , mixed $args [, mixed $... ] )

Among them, $format is the packaging method (that is, the incoming parameters are packed into binary strings according to the specified format), $args are the parameters to be packed.

Specifically, the $format parameter is a format string used to specify the packaging method of data. For example, use H* to convert all parameters into hexadecimal strings.

Here is a sample code to convert a string into bytes:

$str = 'Hello, world!';
$bytes = pack('H*', bin2hex($str));

In the above code, the string $str is converted into hexadecimal string and then use the pack() function to pack it into bytes.

2. Convert bytes into strings

In PHP, you can use the unpack() function to convert bytes into strings.

The syntax of the unpack() function is as follows:

array unpack ( string $format , string $data )

Among them, $format is the unpacking method (that is, unpacking the binary string into data according to the specified format), $data is the data to be unpacked.

Specifically, the $format parameter is a format string used to specify how to unpack the data. For example, use H* to convert binary data into a hexadecimal string.

The following is an example code to convert a byte into a string:

$bytes = "\x48\x65\x6c\x6c\x6f\x2c\x20\x77\x6f\x72\x6c\x64\x21";
$str = unpack('H*', $bytes)[1];

In the above code, a byte $bytes is unpacked into sixteen hexadecimal string, and then use the bin2hex() function to convert it into a string. Note that the return value of the unpack() function is an array, so you need to use [1] to obtain the unpacked string.

Summary

In PHP, conversion between strings and bytes is a very common operation. This article introduces two methods, namely using the pack() function to convert strings into bytes, and using the unpack() function to convert bytes into strings. In actual development, we can flexibly choose the appropriate method for conversion according to needs.

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