SplFixedArray::offsetUnset()

(PHP 5 >= 5.3.0, PHP 7)

Unsets the value at the specified $index

说明

publicSplFixedArray::offsetUnset(int $index) : void

Unsets the value at the specified index.

参数

$index

The index being unset.

返回值

没有返回值。

错误／异常

Throws RuntimeExceptionwhen $index is outside the defined size of the array or when $index cannot be parsed as an integer.

This function assigns NULL to the array element. Its use has no effect on count(). Whereas assigning NULL to an element will have no effect on isset(), offsetUnset() and unset() do. Whereas unsetting an element affects the behaviour of foreach() as applied to an array or an ArrayObject, it has no such effect on SplFixedArray, as demonstrated by the code below.
<?php
class atest extends SplFixedArray {
 public function fill() {
  for ($i = $this->count(); --$i >= 0; ) $this[$i] = $i;
 }
 public function dump() {
  $sep = ' ';
  foreach ($this as $k => $v) {
   echo $sep, "$k: ", (is_null($v) ? 'NULL' : $v);
   if (!isset($this[$k])) echo ' and unset';
   $sep = ', ';
  }
  echo PHP_EOL;
 }
}
$a = new atest(3);
$a->dump(); // 0: NULL and unset, 1: NULL and unset, 2: NULL and unset
$a->fill();
$a->dump(); // 0: 0, 1: 1, 2: 2
$a[1] = NULL;
unset($a[2]);
$a->dump(); // 0: 0, 1: NULL, 2: NULL and unset
?>