How to skip the 1st key in an array loop?

aeran_37667 0
Viewed 94444

I have the following code:

if ($_POST['submit'] == "Next") {
    foreach($_POST['info'] as $key => $value) {
        echo $value;
    }
}

How do I get the foreach function to start from the 2nd key in the array?

arrays php
12 Answers

For reasonably small arrays, use array_slice to create a second one:

foreach(array_slice($_POST['info'],1) as $key=>$value)
{
    echo $value;
}
user_910 
foreach(array_slice($_POST['info'], 1) as $key=>$value) {
    echo $value;
}

Alternatively if you don't want to copy the array you could just do:

$isFirst = true;
foreach($_POST['info'] as $key=>$value) {
    if ($isFirst) {
        $isFirst = false;
        continue;
    }   
    echo $value;
}
tom_222240

If you were working with a normal array, I'd say to use something like

foreach (array_slice($ome_array, 1) as $k => $v {...

but, since you're looking at a user request, you don't have any real guarantees on the order in which the arguments might be returned - some browser/proxy might change its behavior or you might simply decide to modify your form in the future. Either way, it's in your best interest to ignore the ordering of the array and treat POST values as an unordered hash map, leaving you with two options :

  • copy the array and unset the key you want to ignore
  • loop through the whole array and continue when seeing the key you wish to ignore
Sean_McSomething_394130

in loop:

if ($key == 0) //or whatever
   continue;
user_431820

If you're willing to throw the first element away, you can use array_shift(). However, this is slow on a huge array. A faster operation would be

reset($a);
unset(key($a));
staticsan_288320

On a array filled with 1000 elements the difference is quite minimal.

Test:

<?php
function slice($a)
{
    foreach(array_slice($a, 1) as $key)
    {

    }

    return true;
}

function skip($a)
{
    $first = false;

    foreach($a as $key)
    {
        if($first)
        {
            $first = false;
            continue;
        }
    }

    return true;
}

$array = array_fill(0, 1000, 'test');

$t1 = time() + microtime(true);

for ($i = 0; $i < 1000; $i++)
{
    slice($array);
}

var_dump((time() + microtime(true)) - $t1);

echo '<hr />';

$t2 = time() + microtime(true);

for ($i = 0; $i < 1000; $i++)
{
    skip($array);
}

var_dump((time() + microtime(true)) - $t2);
?>

Output:

float(0.23605012893677)

float(0.24102783203125)

user_415960 


foreach($_POST['info'] as $key=>$value) {
    if ($key == 0) { //or what ever the first key you're using is
        continue;
    }  else { 
        echo $value;
    }
}
Admin1

if you structure your form differently 

  <input type='text' name='quiz[first]' value=""/>
  <input type='text' name='quiz[second]' value=""/>

...then in your PHP

if( isset($_POST['quiz']) AND 
    is_array($_POST['quiz'])) {

    //...and we'll skip $_POST['quiz']['first'] 
    foreach($_POST['quiz'] as $key => $val){
      if($key == "first") continue;
      print $val; 
    }
}

...you can now just loop over that particular structure and access rest normally

Admin1
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