比较Php数组中值的位置

Question

$commands = array();

    for($p = 0; $p < $commandCount ; $p++){
          $commands[$p] = $_POST['select'.$p];
    }

So I have this Array $commands. In this Array, a List of Commands is stored. I have to check on which Position the Command "mark" is stored and if a certain command follows after it. Some Example Data which can be in $commands: "mark", "ignore", "pick", "random" How would You do it?

Answer 1

You can use $index = array_search("mark", $commands) which will return the index of the first occurrence of the command "mark" and then you can use $commands[$index + 1] to get the next command in the array.

You will also need to check if $index != null as otherwise it may return the first item in your $commands array because null is interpreted as 0

Answer 2

Here is a demonstration with a battery of test cases to fully express how it works and identify fringe cases: ( Demo Link )

*note, array_search() returns false when the needle is not found.

$commands = array("mark", "ignore", "pick", "random");

$attempts = array("mark", "ignore", "pick", "random", "bonk");
foreach($attempts as $attempt){
    echo "$attempt => ";
    $index=array_search($attempt,$commands);
    //                                    vv---increment the value
    if($index===false || !isset($commands[++$index])){  // not found or found last element
        $index=0;                                      // use first element
    }
    echo $commands[$index],"\n";
}

The "or" ( || ) condition will "short circuit", so if $index is false it will exit the condition without calling the second expression ( isset() ).

Output:

mark => ignore
ignore => pick
pick => random
random => mark
bonk => mark

Answer 3

Just did some double checking you're going to want to assert first that your array contains the value of mark first. array_search will return a false otherwise, and that easily can be translated into 0.

Supporting Documentation :

PHP in_array

PHP array_search

$commands = array("mark", "ignore", "pick", "random");
//checks if $command contains mark, 
//gets first index as per documentation 
//Or sets index to -1, ie No such value exists.
 $index = in_array("mark",$commands) ? array_search("mark",$commands):-1;
//gets the next command if it exists
 $nextCommand = $index!=-1? $commands[++$index]:"Unable to Find Command: mark";