Write a program in PHP to convert hexadecimal and reversely output the string

In programming, you often encounter the need to convert a string to hexadecimal situation, or you need to convert a hexadecimal number into a string. Today we will introduce how to use PHP to write a program to convert a string to hexadecimal and output the string in reverse.

1. Convert a string to hexadecimal

First, we need to write a function to convert a string to hexadecimal. The following is a PHP code example:

function strToHex($string){
    $hex = '';
    for ($i=0; $i < strlen($string); $i ){
        $hex .= dechex(ord($string[$i]));
    }
    return $hex;
}

// test
$str = "Hello, World!";
$hex = strToHex($str);
echo "Convert string to hexadecimal:".$hex;

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In the above code, the strToHex function accepts a string as a parameter, and then uses ordThe function converts each character into an ASCII value, and then uses the dechex function to convert the ASCII value into hexadecimal representation. Finally, all the hexadecimal strings are concatenated and output.

2. Convert hexadecimal to string

Next, we need to write a function to convert hexadecimal to string. The code is as follows:

function hexToStr($hex){
    $string = '';
    for ($i=0; $i < strlen($hex)-1; $i =2){
        $string .= chr(hexdec($hex[$i].$hex[$i 1]));
    }
    return $string;
}

// test
$hex = "48656c6c6f2c20576f726c6421";
$str = hexToStr($hex);
echo "Convert hexadecimal to string:".$str;

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In the above code, the hexToStr function accepts a hexadecimal string as a parameter, and then converts two consecutive Combine the hexadecimal characters into an ASCII value, and then use the chr function to convert the ASCII value into the corresponding character. Concatenate all characters to get the final string output.

3. Complete code example

Integrate the above two functions into a complete PHP script, as shown below:

function strToHex($string){
    $hex = '';
    for ($i=0; $i < strlen($string); $i ){
        $hex .= dechex(ord($string[$i]));
    }
    return $hex;
}

function hexToStr($hex){
    $string = '';
    for ($i=0; $i < strlen($hex)-1; $i =2){
        $string .= chr(hexdec($hex[$i].$hex[$i 1]));
    }
    return $string;
}

// test
$str = "Hello, World!";
$hex = strToHex($str);
echo "Convert string to hexadecimal: ".$hex."
";

$reversedStr = hexToStr($hex);
echo "Reverse output string:".$reversedStr;

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Through the above code example, we can realize the mutual conversion between string and hexadecimal, and can reverse the string output. Such functions are often used in data encryption, data transmission, etc. I hope it will be helpful to you.

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