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PHP

Converting character to code and code to character

All characters, even if they are not available on your keyboard, have a character code. PHP offers four functions to deal with these characters code: ord() and chr() to deal with single-byte characters; mb_ord and mb_chr() to deal with multi-byte characters. The chr() and mb_chr() convert the numeric value into the corresponding character; ord() and mb_ord() returns the numeric value for characters.

  1. ord()
    Show ord() function result on Web Browsers
    Protecting Email Address with ord() function
  2. chr()
  3. mb_ord()
  4. mb_chr()

The ord() function

<?php
 //Syntax
 ord(string $character): int

The ord() function converts the first byte of a string to a value between 0 and 255. For example, a value is 97 and A value is 65:

<?php
 echo ord('a'); //Prints: 97
 echo ord('A'); //Prints: 65

This function converts the single-byte characters, use the mb_ord() function if you are dealing with multi-byte characters.

Show ord() function result on Web Browsers

Use the HTML entities syntax and the web browser will automatically decode the number into the relevant character. For example, the ASCII value/code of B is 66, the HTML entity &#66; displays B on a browser page, see example:

<?php
 echo '&#66;&#114;&#97;&#105;&#110;&#66;&#101;&#108;&#108;';
 //Prints: BrainBell
The HTML entities

Protecting Email Address

The following code can be used to protect email addresses from spammers. Using HTML entities for email addresses, making it much harder for spam bots to find email addresses from web pages:

<?php
 $str = 'admin@BrainBell.com';
 $str2 = '';
 for ($i=0; $i<strlen($str); $i++)
  $str2 .= '&#'.ord($str[$i]).';'; 

 echo $str2;
Protecting email address with ord() function in PHP

The chr() function

<?php
 //Syntax
 chr(int $codepoint): string

The chr() function does the reverse of ord() function, it generates a single-byte string from a number (0-255), use mb_chr() function if you are dealing with multi-byte characters. In the following example, we used chr() function to generate the entire alphabet:

<?php
 for ($a=65; $a<(91); $a++) { 
  echo chr($a); 
 }
//ABCDEFGHIJKLMNOPQRSTUVWXYZ

mb_ord()

<?php
 //Syntax
 mb_ord(string $string, ?string $encoding = null): int|false

This function has two parameters:

  1. $string: the input string
  2. $encoding (optional): the character encoding. If null or not provided, the internal character encoding value will be used.

The mb_ord() function returns the Unicode code point value of the given character. The code point value is a numerical value that maps to a specific character.

<?php
 echo mb_ord('€') . "\n";
 //Prints: 8364
 
 echo mb_ord('£') . "\n";
 //Prints: 163
 
 echo mb_ord('Ͻ', 'UTF-8') . "\n";
 //Prints: 1021
 
 echo mb_ord('ڻ', 'UTF-8') . "\n";
 //Prints: 1723
 
 echo mb_ord('➿', 'UTF-8') ."\n";
 //Prints: 10175

mb_chr()

<?php
 //Syntax
 mb_chr(int $codepoint, ?string $encoding = null): string|false

This function has two parameters:

  1. $codepoint: A Unicode codepoint value
  2. $encoding (optional): the character encoding. If null or not provided, the internal character encoding value will be used.

The mb_chr() function does the reverse of mb_ord() function, it generates a multi-byte string from a number (Unicode codepoint value), use chr() function if you are dealing with single-byte characters.

<?php

 echo mb_chr('8364') . "\n";
 //Prints: €
 
 echo mb_chr('163') . "\n";
 //Prints: £
 
 echo mb_chr('1021', 'UTF-8') . "\n";
 //Prints: Ͻ
 
 echo mb_chr('1723', 'UTF-8') . "\n";
 //Prints: ڻ
 
 echo mb_chr('10175', 'UTF-8') ."\n";
 //Prints: ➿

Manipulating Strings:

  1. Changing string case
  2. Comparing Strings
  3. Comparing Strings with Natural Order Algorithm
  4. Converting Strings into HTML
  5. Converting HTML Entities and Special Characters
  6. Formatting Strings
  7. Padding Strings
  8. Replacing Newlines with BR Tag and Trimming Whitespaces
  9. Converting character to code and code to character
  10. Repeat and Shuffle a String
  11. Count Characters and Words
  12. Manipulating substrings