How to convert a set of characters using strtr function in PHP

The strtr function in PHP is a powerful function for character conversion. It can convert a set of characters from one character set to another, or it can replace specific characters in a string with another character by using a conversion table. This article will introduce how to use the strtr function in PHP to convert a set of characters.

1. Basic usage of strtr function

The basic syntax of strtr function is as follows:

string strtr ( string $str , string|array $replace_pairs )

Among them, the $str parameter is the string to be converted. , the $replace_pairs parameter is an array or string containing the character pairs to be replaced.

Here is a basic example:

$str = "Hello, world!";
$replace_pairs = array("H" => "J", "l" => "b", "!" => "?");
echo strtr($str, $replace_pairs);
// 输出：Jeppo, worbd?

2. Replace a specific character in a string with another character

In addition to using an array to specify the character In addition to pairs, the strtr function can also use a string parameter to specify the characters to be replaced and the new characters. The form of each character pair is as follows: "Original character => new character". The following example will replace "A" with "B" in a string:

$str = "AAAABBBBBCCCCCDDDDD";
echo strtr($str, "AB");
// 输出：BBBBBBBBCCCCCDDDDD

3. Convert character set

The strtr function can also be used to convert a character from a character set Convert a character set to another character set. For example, to convert a string from the UTF-8 character set to the ISO-8859-1 character set:

$str = "你好，世界！";
echo strtr($str, "你好，世界！", "Ni Hao, Shijie!");
// 输出：Ni Hao, Shijie!

4. Character pairs in the form of an array

In addition to representing the character pairs In addition to a string of the form "original character => new character", you can also use an array to specify character pairs. This method is more flexible because character pairs in array form can be specified in batches and carry other data.

The following is an example of using an array to specify a character pair:

$str = "Hello, world!";
$replace_pairs = array(
    "H" => "J",
    "l" => "b",
    "!" => "?",
    "o" => array("a", "b", "c")
);
echo strtr($str, $replace_pairs);
// 输出：Jeppa, warbd?

In this example, the new character corresponding to the character "o" is specified as an array. This means that each "o" in the original string will be replaced with the next value in the new character array.

5. Replace using regular expressions

The strtr function can use regular expressions very flexibly to convert characters according to patterns. For example, the following code will replace all numbers in a string using a regular expression:

$str = "I am 26 years old.";
$replace_pairs = array("0", "1", "2", "3", "4", "5", "6", "7", "8", "9");
echo strtr($str, array_combine(range(0, 9), $replace_pairs));
// 输出：I am twenty-six years old.

In this example, range(0,9) returns an array containing numbers from 0 to 9, array_combine() The function merges it with the $replace_pairs array. The end result is that the numeric string is replaced with the corresponding text.

6. Summary

The strtr function is a powerful character conversion tool in PHP, which allows you to convert characters using multiple forms of character pairs. Using advanced techniques such as regular expressions allows you to handle character conversions more flexibly. The above examples show some basic usage of the strtr function, and hope to help you better understand and use this function.

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