PHP 8.1.9 Released!

The UnderflowException class

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

Einführung

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

Klassenbeschreibung

class UnderflowException extends RuntimeException {
/* Geerbte Eigenschaften */
protected string $message = "";
private string $string = "";
protected int $code;
protected string $file = "";
protected int $line;
private array $trace = [];
private ?Throwable $previous = null;
/* Geerbte Methoden */
final public Exception::getMessage(): string
final public Exception::getCode(): int
final public Exception::getFile(): string
final public Exception::getLine(): int
final public Exception::getTrace(): array
final public Exception::getTraceAsString(): string
public Exception::__toString(): string
private Exception::__clone(): void
}
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User Contributed Notes 2 notes

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Jakub Adamczyk
30 days 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 ...
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-8
evguenia dot chagnon at gmail dot com
5 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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