PHP/Data Structure/array key exists
Содержание
<source lang="html4strict">
if (! array_key_exists($_POST["order"], $GLOBALS["sweets"])) {
$errors[] = "Please choose a valid order.";
}
</source>
Checking for an element with a particular key
<source lang="html4strict">
<? $meals = array("A" => 1,
"B" => 4.95, "C" => 3.00, "D" => 6.50, "E" => 0); // Shrimp Puffs are free!
$books = array("F","G"); if (array_key_exists("A",$meals)) {
print "Yes, we have A";
} if (array_key_exists("B",$meals)) {
print "We have a B";
} if (array_key_exists(1, $books)) {
print "Element 1 is How to Cook in Eat in Chinese";
} ?>
</source>
Testing for the Existence of a Key in an Array
<source lang="html4strict">
<?php $countries = array("Germany" => "German", "France" => "French", "Spain" => "Spanish"); $country = "asdf";
printf("%s of our visitors are from %s.
\n", array_key_exists($country, $countries) ? "Some" : "None", $country);?>
</source>
<source lang="html4strict">
<?php $choices = array("eggs" => "E",
"toast" => "T", "coffee" => "C");
echo "<select name="food">\n"; foreach ($choices as $key => $choice) {
echo "<option value="$key">$choice</option>\n";
} echo "</select>"; if (! array_key_exists($_POST["food"], $choices)) {
echo "You must select a valid choice.";
} ?>
</source>