如何显示特定的阵列组合？

Question

i want to display following array in output as 246,357 that is donot process first subarray and also the remaining subarray combination should be like $array[1][0].$array[2][0].$array[3][0],similarly combination should be $array[1][1].$array[2][1].$array[3][1]

$array=[
          [0,1],
          [2,3],
          [4,5],
          [6,7]
       ];

i have written follwing code but could not bypass first subarray so my output is 0246,1357.plz help.

foreach($array as $n)
{
    $a.=$n[0];
    $b.=$n[1];
}
echo "$a".","."$b";

Answer 1

One way to skip the first element would be to use a flag variable $first:

$first = true;
foreach ($array as $n) {
    if ($first) {
        $first = false;
    } else {
        $a .= $n[0];
        $b .= $n[1];
    }
}

Another way would be to remove the first element from the array, so it will be skipped over:

unset($array[0]);

Or check the key from within the foreach loop:

foreach ($array as $k => $n) {
    if ($k > 0) {
        $a .= $n[0];
        $b .= $n[1];
    }
}

Yet another way would be to use array_shift(), which changes numeric keys in addition to removing the first element:

array_shift($array);

Finally, because your array contains only consecutive integer keys starting from 0, you could just use a normal for loop:

for ($i = 1; $i < count($array); $i++) {
    $a .= $array[$i][0];
    $b .= $array[$i][1];
}