How to perform ASCII encoding and character conversion in php

In PHP development, we often need to convert character encodings. ASCII encoding is one of the most common encodings. It is the most basic character encoding and includes common English letters, numbers, punctuation marks and other characters. This article will introduce how to perform ASCII encoding and character conversion in PHP to help developers better understand and apply it.

1. Introduction to ASCII encoding

ASCII encoding (American Standard Code for Information Interchange) is one of the most basic character encodings. It was formulated by the United States and uses 7-bit binary numbers (128 characters in total) ), can represent common characters such as uppercase English letters, lowercase English letters, numbers, punctuation marks, control characters, etc. Each character has a unique binary representation. ASCII encoding is generally used for English character sets and does not include non-English characters, such as Chinese characters.

2. Convert ASCII encoding to characters

In PHP, you can use the chr() function to convert ASCII encoding into corresponding characters. The syntax of the chr() function is as follows:

chr($ascii);

Among them, $ascii is the ASCII encoding value, and the value range is 0-127.

For example, convert the ASCII code 97 into the corresponding characters:

echo chr(97);

The output result is: a

At the same time, you can also use the ord() function to convert the characters into the corresponding ASCII encoded value. The syntax of the ord() function is as follows:

ord($char);

Among them, $char is a character, which can only be one character.

For example, convert character a to the corresponding ASCII code:

echo ord('a');

The output result is: 97

3. Convert string to ASCII code

In In PHP, you can also use the ord() function to convert each character of the string into the corresponding ASCII encoded value and return an ASCII encoded integer array.

$str = "Hello World";
$ascii_arr = array();
for($i=0; $i<strlen($str); $i++){
    $ascii_arr[] = ord($str[$i]);
}
print_r($ascii_arr);

Output result:

Array
(
    [0] => 72
    [1] => 101
    [2] => 108
    [3] => 108
    [4] => 111
    [5] => 32
    [6] => 87
    [7] => 111
    [8] => 114
    [9] => 108
    [10] => 100
)

4. ASCII encoding to string

In PHP, you can use the chr() function to convert the ASCII encoding array into the corresponding string .

$ascii_arr = array(72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100);
$str = "";
foreach($ascii_arr as $ascii){
    $str .= chr($ascii);
}
echo $str;

The output result is: Hello World

5. ASCII encoding conversion

In PHP, you can also use functions such as iconv() function and mb_convert_encoding() function to perform ASCII encoding and other common encodings.

$ascii_str = "Hello World";
// ASCII转GB2312
$gbk_str = iconv("ASCII", "GB2312", $ascii_str);
echo $gbk_str; // 输出结果为：Hello World

// ASCII转UTF-8
$utf8_str = mb_convert_encoding($ascii_str, "UTF-8", "ASCII");
echo $utf8_str; // 输出结果为：Hello World

The above codes convert ASCII encoded strings into GB2312 encoding and UTF-8 encoding respectively.

6. Summary

This article introduces some methods for converting ASCII encoding and characters in PHP, including ASCII encoding to characters, string to ASCII encoding, ASCII encoding to string and ASCII Coding conversion and other related skills. In the actual development process, through these methods, character encoding issues can be better handled to ensure that the application can correctly handle various character sets and encodings.

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