How to convert value to hexadecimal in php and output in reverse

php method to convert the value to hexadecimal and reverse output: 1. Use the dechex() or base_convert() function to convert the value to hexadecimal, the syntax "$str=dechex($number) ;" or "$str=base_convert($number,10,16);"; 2. Use the strrev() function and echo to reversely output the obtained hexadecimal value, the syntax is "echo strrev($str);".

The operating environment of this tutorial: windows7 system, PHP8 version, DELL G3 computer

php converts the value to hexadecimal and outputs it in reverse It can be divided into two steps:

• Step 1: Convert the value to hexadecimal

• Step 2: Reverse the hexadecimal value output

Let’s implement it step by step.

Step 1: Convert the value to hexadecimal

PHP provides two functions for conversion:

• dechex() function

• base_convert() function

1. dechex() function conversion

dechex() function converts decimal numbers to hexadecimal numbers.

dechex(number);

Return value: a string containing a hexadecimal number with a decimal value.

Example:

<?php
$num1=1587;
echo dechex($num1) . "<br>";

$num2=30;
echo dechex($num2) . "<br>";
?>

Description:

hexdec() Converts a hexadecimal string to a decimal number. The maximum value that can be converted is 7ffffffff, which is 2147483647 in decimal. Starting with PHP 4.1.0, this function can handle large numbers, in which case it returns a float type.

hexdec() Replaces all non-hexadecimal characters encountered with 0. This way, all zeros on the left are ignored, but zeros on the right are included in the value.

2. base_convert() function conversion

base_convert() function converts numbers between arbitrary bases.

base_convert(number,frombase,tobase);

Parameters	Description
number	Required . Specifies the number to be converted.
frombase	Required. Specifies the original base of the number. Between 2 and 36 (inclusive). Numbers above decimal are represented by the letters a-z, such as a for 10, b for 11, and z for 35.
tobase	Required. Specifies the base to be converted. Between 2 and 36 (inclusive). Numbers above decimal are represented by the letters a-z, such as a for 10, b for 11, and z for 35.

When the value of parameter tobase is 16, other base numbers can be converted into hexadecimal numbers.

Example:

<?php
$num1=1587;
echo base_convert($num1, 10, 16) . "<br>";

$num2=30;
echo base_convert($num2, 10, 16). "<br>";
?>

Step 2: Reverse the obtained hexadecimal value and output it

Reverse output is to invert the value and then use echo to output it.

In PHP, you can use the strrev() function to reverse the string and reverse the order of characters in the string.

Syntax:

strrev($string)

Parameters	Description
string	Required. Specifies the string to reverse.

#This function only accepts one required parameter "$string" for the reverse operation.

• If the operation is successful, the reversed string will be returned.

Example:

<?php
header("Content-type:text/html;charset=utf-8");
$num1=1587;
echo "原数据：".$num1 . "<br>";
$str1=base_convert($num1, 10, 16);
echo "16进制值：".$str1 . "<br>";
echo "反转后：".strrev($str1). "<br>";

echo "<hr>";

$num2=30;
$str2=base_convert($num2, 10, 16);
echo "原数据：".$num2 . "<br>";
echo "16进制值：".$str2 . "<br>";
echo "反转后：".strrev($str2). "<br>";
?>

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