php数组函数array_key_exists()小结

(编辑：jimmy 日期: 2025/10/21 浏览：2)

array_key_exists()函数判断某个数组中是否存在指定的key，如果key存在，则返回true，否则返回flase

array_key_exists(key,array);

key：必需。规定键名
array：必需。规定输入的数组

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<" ", microtime());
return ((float)$usec + (float)$sec);
}
$test_arr['aa']='dd';
$test_arr['bb']='';
$test_arr['cc']=NULL;
$test_arr['dd']=false;
$test_arr= array('aa'=>'dd','bb'=>'','cc'=>null,'dd'=>false);
echo "isset aa is ";var_dump(isset($test_arr['aa']));echo "n";
echo "isset bb is ";var_dump(isset($test_arr['bb']));echo "n";
echo "isset cc is ";var_dump(isset($test_arr['cc']));echo "n";
echo "isset dd is ";var_dump(isset($test_arr['cc']));echo "n";
echo "isset none is ";var_dump(isset($test_arr['none']));echo "n";
echo "key_exist aa is ";var_dump(array_key_exists('aa',$test_arr));echo "n";
echo "key_exist bb is ";var_dump(array_key_exists('bb',$test_arr));echo "n";
echo "key_exist cc is ";var_dump(array_key_exists('cc',$test_arr));echo "n";
echo "key_exist dd is ";var_dump(array_key_exists('dd',$test_arr));echo "n";
echo "key_exist none is ";var_dump(array_key_exists('none',$test_arr));echo "n";
$time_start = microtime_float();
for($i=0;$i<100;$i++){
isset($test_arr['aa']);
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "isset 100 is $timen";
for($i=0;$i<10000;$i++){
isset($test_arr['aa']);
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "isset 10000 is $timen";
for($i=0;$i<1000000;$i++){
isset($test_arr['aa']);
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "isset 1000000 is $timen";
//++++++++++++++++++++++++++++++
$time_start = microtime_float();
for($i=0;$i<100;$i++){
array_key_exists('aa',$test_arr);
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "array_key_exists 100 is $timen";
for($i=0;$i<10000;$i++){
array_key_exists('aa',$test_arr);
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "array_key_exists 10000 is $timen";
for($i=0;$i<1000000;$i++){
array_key_exists('aa',$test_arr);
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "array_key_exists 1000000 is $timen";

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