PHP: Delete all array elements before a specific one

Question

Hi I've got the following array:

$days = array(
            1=>"Sunday",
            2=>"Monday",
            3=>"Tuesday",
            4=>"Wednesday",
            5=>"Thursday",
            6=>"Friday",
            7=>"Saturday"
            );

Now I want to make a loop that automatically removes all objects before number 4.
I tried this:

$startIndex = 4;
for($i = 1; $days < $startIndex; $i++)
{
    unset($days[$i]);
}

But it does not work.

have you looked at array_splice? ie: array_splice( $days,0, 4 ); — Professor Abronsius
– Professor Abronsius, Commented Nov 11, 2015 at 9:22

syck · Accepted Answer · 2015-11-11 09:52:17Z

7

A shorter solution may be given using array_slice():

$days = array(
            1=>"Sunday",
            2=>"Monday",
            3=>"Tuesday",
            4=>"Wednesday",
            5=>"Thursday",
            6=>"Friday",
            7=>"Saturday"
            );


$startIndex = 4;
$days = array_slice($days, $startIndex-1, NULL, TRUE);

print_r($days);

returns

Array
(
    [4] => Wednesday
    [5] => Thursday
    [6] => Friday
    [7] => Saturday
)

answered Nov 11, 2015 at 9:52

syck

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Comments

Marcin · Accepted Answer · 2015-11-11 09:24:24Z

3

Change $days to $i as $i is your index value.

$days = array(
            1=>"Sunday",
            2=>"Monday",
            3=>"Tuesday",
            4=>"Wednesday",
            5=>"Thursday",
            6=>"Friday",
            7=>"Saturday"
            );


$startIndex = 4;
for($i = 1; $i < $startIndex; $i++)
{
    unset($days[$i]);
}

print_r($days);

edited Nov 11, 2015 at 9:24

answered Nov 11, 2015 at 9:22

Marcin

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Comments

André Ferraz · Accepted Answer · 2015-11-11 09:50:45Z

0

Your array

$days = array
(
     1=>"Sunday",
     2=>"Monday",
     3=>"Tuesday",
     4=>"Wednesday",
     5=>"Thursday",
     6=>"Friday",
     7=>"Saturday"
);

Loop to remove all element before a specified index.

# Number to stop the unset.
$split_number =4;
# Loop through array

for($a=0;$a<sizeof($days);$a++)
{
    if($a < $split_number)
        # Unset element if condition is true
        unset($days[$a]);
}

print_r($days);

Result

Array
(
    [4] => Wednesday
    [5] => Thursday
    [6] => Friday
    [7] => Saturday
)

If you wish the indexes to start from 0 again, you can use the array_values

answered Nov 11, 2015 at 9:50

André Ferraz

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