小编leo*_*old的帖子

在1维数组中使用array_search很简单

$array = array("apple", "banana", "cherry");
$searchValue = "cherry";
$key = array_search($searchValue, $array);

echo $key;

但是多维数组怎么样？

    #RaceRecord

    [CarID] [ColorID] [Position]
[0]    1        1         3
[1]    2        1         1
[2]    3        2         4
[3]    4        2         2
[4]    5        3         5

例如,我想得到位置为1的汽车的索引.我该怎么做？

尝试执行do-release-upgrade从 Ubuntu 18.04 升级到 20.04 时，出现以下错误

Checking for a new Ubuntu release
Get:1 Upgrade tool signature [1,554 B]                                                                                                 
Get:2 Upgrade tool [1,342 kB]                                                                                                          
Fetched 1,343 kB in 0s (0 B/s)                                                                                                         
authenticate 'focal.tar.gz' against 'focal.tar.gz.gpg' 
Authentication failed
Authenticating the upgrade failed. 
There may be a problem with the network or with the server.

仅供参考：我已经试过了sudo apt-get install --reinstall ubuntu-keyring。