ASCII to numeric PHP conversion techniques

ASCII to numerical PHP conversion skills

In PHP programming, sometimes we need to convert ASCII codes into corresponding numerical values. This is when processing strings and encryption It is often used in operations such as decryption. This article will introduce some simple and effective PHP conversion techniques, and attach code examples for reference.

ASCII code introduction

ASCII (American Standard Code for Information Interchange) is a character set standard for computer encoding. It converts each character into a A unique numeric value, usually in the range 0 to 127. In the ASCII code, the numbers 0 to 9 correspond to numeric values ​​​​from 48 to 57, the uppercase letters A to Z correspond to numeric values ​​​​from 65 to 90, and the lowercase letters a to z correspond to numeric values ​​​​from 97 to 122.

ASCII converted to numerical value

In PHP, you can use the built-in function ord() to convert characters into corresponding ASCII code values, also Characters can be converted to integer values ​​through (int)casting.

// 使用 ord() 函数将字符转换为 ASCII 码
$char = 'A';
$ascii_value = ord($char);
echo "字符 $char 的 ASCII 码值为：$ascii_value
";

// 使用 (int) 强制转换将字符转换为整数
$char = '5';
$int_value = (int)$char;
echo "字符 $char 的整数值为：$int_value
";

Convert numerical values ​​to ASCII

In contrast to converting ASCII to numerical values, we can convert the ASCII code value to the corresponding value through the chr() function character of. Alternatively, you can use the sprintf() function to convert integer values ​​to characters.

// 使用 chr() 函数将 ASCII 码值转换为字符
$ascii_value = 97;
$char = chr($ascii_value);
echo "ASCII 码值 $ascii_value 对应的字符为：$char
";

// 使用 sprintf() 函数将整数值转换为字符
$int_value = 8;
$char = sprintf('%c', $int_value);
echo "整数值 $int_value 对应的字符为：$char
";

Application example: simple encryption and decryption

The following is a simple encryption and decryption example, which simply encrypts and decrypts the input string.

function encrypt($str){
    $encrypted_str = '';
    for($i=0; $i<strlen($str); $i++){
        $encrypted_str .= chr(ord($str[$i])+1); // 将每个字符的 ASCII 码加1
    }
    return $encrypted_str;
}

function decrypt($str){
    $decrypted_str = '';
    for($i=0; $i<strlen($str); $i++){
        $decrypted_str .= chr(ord($str[$i])-1); // 将每个字符的 ASCII 码减1
    }
    return $decrypted_str;
}

$input = 'Hello, PHP!';
$encrypted = encrypt($input);
$decrypted = decrypt($encrypted);

echo "原始字符串：$input
";
echo "加密后的字符串：$encrypted
";
echo "解密后的字符串：$decrypted
";

The above is about the method of converting ASCII code into numerical value in PHP and a simple encryption and decryption example. In practical applications, we can choose the appropriate conversion method according to the specific situation to meet the needs of programming. I hope this article can help readers understand and master the conversion skills between ASCII codes and numerical values.

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