w3resource

PHP: rtrim() function

Description

The rtrim() function is used to remove the whitespaces and other predefined characters from the right side of a string.

Version:

(PHP 4 and above)

Syntax:

rtrim(string_name, char_list)

Parameter:

Name Description Required /
Optional
Type
string_name The string that will be trimmed. Required String
char_list Specifies which character to remove from the string. Without this parameter, the function removs the following characters.
" " an ordinary space
"\0" - the NUL-byte
\t" - tab
\n" - line feed
\x0B" - a vertical tab
"\r" - a carriage return
Optional String

Return value:

Returns the modified string.

Value Type: String.

Pictorial Presentation

php-string-rtrim()

Example:

<?php
$text1="w3resource.com  ";
$text2="w3resource.com\t\t";
$text3="\t\tw3resource.com\x0A";
$text4="Good Morning"; 
$trimmed_text=rtrim($text1);
var_dump($trimmed_text);
echo '<br>';
$trimmed_text=rtrim($text2);
var_dump($trimmed_text);
echo '<br>';
$trimmed_text=rtrim($text3);
var_dump($trimmed_text);
echo '<br>';
$trimmed_text=rtrim($text1,'w3');
var_dump($trimmed_text);
echo '<br>';
$trimmed_text=rtrim($text4,"ng");
var_dump($trimmed_text);
?>

Output :

string(14) "w3resource.com"
string(14) "w3resource.com"
string(16) "w3resource.com"
string(16) "w3resource.com"
string(10) "Good Morni"

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.

Notes/Caveats:

  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