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    The UnderflowException class

    (PHP 5 >= 5.1.0, PHP 7)

    Introducere

    Exception thrown when performing an invalid operation on an empty container, such as removing an element.

    Sinopsisul clasei

    UnderflowException extends RuntimeException {
    /* Proprietăți moștenite */
    protected string $message ;
    protected int $code ;
    protected string $file ;
    protected int $line ;
    /* Metode moștenite */
    public Exception::__construct ( string $message = "" , int $code = 0 , Throwable $previous = null )
    final public Exception::getMessage ( ) : string
    final public Exception::getPrevious ( ) : Throwable
    final public Exception::getCode ( ) : mixed
    final public Exception::getFile ( ) : string
    final public Exception::getLine ( ) : int
    final public Exception::getTrace ( ) : array
    final public Exception::getTraceAsString ( ) : string
    public Exception::__toString ( ) : string
    final private Exception::__clone ( ) : void
    }
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    User Contributed Notes 2 notes

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    0
    Jakub Adamczyk
    2 years ago
    The most typical usage is with stack, queue or collection, for example when you queue tasks, make call stack or manipulate JSON, XML, etc. elements.

    As other exepctions of RuntimeException class, this type of error can't be detected in (for example) your IDE or compiler.

    <?php
    // Functions declared above
    $f1 = function() { setTypeControl('username');};
    $f2 = function() { setTypeControl('userpass');};
    $f3 = function() { setButton('Add');};
    $f4 = function() { setButton('OK');};

    $tasks = new class {
        private     $list;

            // Create internal queue
            public function __construct() {
                $this->list = new SplQueue;
        }

            // Add to queue
            public function add(callable $func) {
                $this->list->enqueue($func);
        }

            // Delete from queue and execute
            public function do() {
            if (    $this->list->isEmpty()) {
                throw new     UnderflowException;
            } else {
                    call_user_func($this->list->dequeue());
            }
        }

    };

    $tasks->add($f1);
    $tasks->add($f2);
    $tasks->add($f3);
    $tasks->add($f4);

    $tasks->do(); // Field username is created
    $tasks->do(); // Field userpass is created
    $tasks->do(); // Button Add is created
    $tasks->do(); // Button OK is created
    $tasks->do(); // Fatal error: Uncaught UnderflowException in ...
    up
    -9
    evguenia dot chagnon at gmail dot com
    7 years ago
    UnderflowException handles exceptions due to a value being too small to maintain precision, resulting in loss of accuracy. In PHP, this can occurs when using floats:

    echo (1-0.9) // 0.1
    echo (1-0.99) // 0.01
    echo (1-0.999) // 0.001
    echo (1-0.9999) // 9.9999999999989E-05
    echo (1-0.99999) // 9.9999999999545E-06
    echo (1-0.999999) // 1.0000000000288E-06
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