PHP String strtr() Function

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The PHP String strtr() function is used to replace a substring in a string with a given string of characters. It also allows you to replace a particular word in a string with another. This function is case sensitive.

Syntax

Below is the syntax of the PHP String strtr() function −

string strtr ( string $string, string $from, string $to )

Alternative signature −

string strtr ( string $string, array $array )

Parameters

Here are the parameters of the strtr() function −

• $string − (Required) It is the string being translated.

• $from − (Required) It is the string being translated to 'to'.

• $to − (Required) It is the string replacing from.

• $array − (Required) The array option can be used instead of to and from, in which case it takes the form of an array.

Return Value

The strtr() function returns the translated string. If the array parameter contains an empty string ("") as a key, the function returns FALSE.

PHP Version

First introduced in core PHP 4, the strtr() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

Here is the basic example of the PHP String strtr() function to replace the characters from the given string.

<?php
   echo strtr("Hilla Warld","ia","eo");
?>

Output

Here is the outcome of the following code −

Hello World

Example 2

The following program replaces characters in a string using strtr()'s $from and $to parameters. It converts each character in $from to its equivalent character in $to.

<?php
   // Define string here
   $string = "hello world";
   
   // Vowels to replace
   $from = "aeiou"; 
   
   // Numbers replacing vowels
   $to = "12345";   

   // Replace characters
   $result = strtr($string, $from, $to);

   echo "Original String: $string\n";
   echo "Translated String: $result\n";
?> 

Output

This will generate the below output −

Original String: hello world
Translated String: h2ll4 w4rld

Example 3

This program replaces substrings with an associative array using the strtr() function. Each key in the array is replaced with its respective value.

<?php
   // Define string here
   $string = "hello world";

   // Define substrings to replace
   $replacements = [
      "hello" => "hi",
      "world" => "universe"
   ];

   // Replace substrings
   $result = strtr($string, $replacements);

   echo "Original String: $string\n";
   echo "Translated String: $result\n";
?> 

Output

This will create the below output −

Original String: hello world
Translated String: hi universe

Example 4

This program shows how overlapping keys in an array will be handled when you are using the strtr() function. The longer keys are replaced first.

<?php
   // Define the string here
   $string = "abcdef";

   // Define replacements
   $replacements = [
      // Longer key
      "abc" => "123", 
      
      // Shorter key
      "a" => "X",     
      "def" => "456"
   ];

   // Replace substrings
   $result = strtr($string, $replacements);

   echo "Original String: $string\n";
   echo "Translated String: $result\n";
?> 

Output

Following is the output of the above code −

Original String: abcdef
Translated String: 123456