PHP: strtr() function


The strtr() function is used to translate certain characters in a string.


(PHP 4 and above)


strtr(string_name, from_string, to_string) 


Name Description Required /
string_name The string to be translated. Required String
from_string Contains characters to be translated. Required String
to_string Contains characters to be translated with. Required String

Another Syntax:

strtr(string_namer, translating_array)


Name Description Required /
string_name The string to be translated Required String
translating_array Contains key value pairs. If values of the array elements are matched in the input string, then those characters in the input string are replaced with the corresponding keys of those values. Required Array

Return value:

Returns the translated string.

Value Type: String.

Pictorial Presentation



$string = 'Good Marning....';
echo  strtr($string, 'Ma', 'mo');


Good morning....

View the example in the browser

See also

PHP Function Reference

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PHP: Tips of the Day

PHP - How do I implement a callback in PHP?

The manual uses the terms "callback" and "callable" interchangeably, however, "callback" traditionally refers to a string or array value that acts like a function pointer, referencing a function or class method for future invocation. This has allowed some elements of functional programming since PHP 4. The flavors are:

$cb1 = 'someGlobalFunction';
$cb2 = ['ClassName', 'someStaticMethod'];
$cb3 = [$object, 'somePublicMethod'];

// this syntax is callable since PHP 5.2.3 but a string containing it
// cannot be called directly
$cb2 = 'ClassName::someStaticMethod';
$cb2(); // fatal error

// legacy syntax for PHP 4
$cb3 = array(&$object, 'somePublicMethod');

This is a safe way to use callable values in general:

if (is_callable($cb2)) {
    // Autoloading will be invoked to load the class "ClassName" if it's not
    // yet defined, and PHP will check that the class has a method
    // "someStaticMethod". Note that is_callable() will NOT verify that the
    // method can safely be executed in static context.

    $returnValue = call_user_func($cb2, $arg1, $arg2);

Modern PHP versions allow the first three formats above to be invoked directly as $cb(). call_user_func and call_user_func_array support all the above.


  1. If the function/class is namespaced, the string must contain the fully-qualified name. E.g. ['Vendor\Package\Foo', 'method']
  2. call_user_func does not support passing non-objects by reference, so you can either use call_user_func_array or, in later PHP versions, save the callback to a var and use the direct syntax: $cb();
  3. Objects with an __invoke() method (including anonymous functions) fall under the category "callable" and can be used the same way, but I personally don't associate these with the legacy "callback" term.
  4. The legacy create_function() creates a global function and returns its name. It's a wrapper for eval() and anonymous functions should be used instead.

Ref : https://bit.ly/2Zmqil0