Quickly learn about ASCII value conversion in PHP

ASCII value conversion in PHP is a problem often encountered in programming. ASCII (American Standard Code for Information Interchange) is a standard encoding system for converting characters into numbers. In PHP, we often need to convert between characters and numbers through ASCII code. This article will introduce how to convert ASCII values ​​in PHP and give specific code examples.

1. Convert characters to ASCII values

In PHP, we can use the ord() function to convert characters to ASCII values. The ord() function accepts a character as a parameter and returns the corresponding ASCII code value. The following is a simple sample code:

$char = 'A';
$asciiValue = ord($char);
echo "字符'{$char}'对应的ASCII数值为：{$asciiValue}";

In this example, we convert the character 'A' to the corresponding ASCII value and output the result. In this way, we can easily convert characters into corresponding ASCII code values.

2. Convert ASCII values ​​to characters

In contrast to converting characters to ASCII values, we can use the chr() function to convert ASCII values ​​to characters. The chr() function accepts an ASCII code value as a parameter and returns the corresponding character. The following is a sample code:

$asciiValue = 65;
$char = chr($asciiValue);
echo "ASCII数值{$asciiValue}对应的字符为：{$char}";

In this example, we convert the ASCII value 65 into the corresponding characters and output the result. Through the chr() function, we can easily convert ASCII values ​​into corresponding characters.

3. Practical application example

Below we give a practical application example to encrypt and decrypt strings through ASCII numerical conversion. We will use a simple encryption algorithm that adds a fixed offset to the ASCII value of each character of the string to encrypt and decrypt.

function encrypt($string, $offset) {
    $encryptedString = '';
    for ($i = 0; $i < strlen($string); $i++) {
        $char = $string[$i];
        $asciiValue = ord($char);
        $encryptedAscii = $asciiValue + $offset;
        $encryptedChar = chr($encryptedAscii);
        $encryptedString .= $encryptedChar;
    }
    return $encryptedString;
}

function decrypt($string, $offset) {
    return encrypt($string, -$offset);
}

// 加密字符串
$string = 'Hello, World!';
$offset = 3;
$encryptedString = encrypt($string, $offset);
echo "加密后的字符串为：{$encryptedString}
";

// 解密字符串
$decryptedString = decrypt($encryptedString, $offset);
echo "解密后的字符串为：{$decryptedString}
";

In this example, we define the encrypt() and decrypt() functions to implement string encryption and decryption operations, and process characters through ASCII numerical conversion. In this way, we can quickly implement simple encryption and decryption functions.

Summary

In PHP, the ord() and chr() functions can be used to quickly and easily convert between characters and ASCII values. Through practical application examples, we can more intuitively understand how to use ASCII numerical conversion to achieve some interesting functions. I hope this article will be helpful to you when dealing with ASCII value conversion problems in PHP development.

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