Compare one array with another and replace missing values php

Question

I have two Arrays:

$a1=array("Maths","English","Science","ICT");
$a2=array("Maths","ICT");

I want to compare $a1 with $a2, then return

$a3=array("Maths",",,",",,","ICT");

So replace the missing values in $a2 with ",,"

This is my meager attempt :(

$a1=array("Maths","English","Science","ICT");
$a2=array("Maths","ICT");
$result = array_diff($a1, $a2);
foreach ($result as $v){
$a3 = str_replace($v, ",,", $a1);
}
print_r($a3);

Dave Chen · Accepted Answer · 2014-10-21 23:39:36Z

1

Glad you figured it out, but I think this might work better:

<?php

$a1 = array("Maths", "English", "Science", "ICT");
$a2 = array("Maths", "ICT");

$a3 = $a1;

$keys = array_keys(array_diff($a1, $a2));
foreach ($keys as $key)
    $a3[$key] = ',,';

print_r($a3);

Output:

Array
(
    [0] => Maths
    [1] => ,,
    [2] => ,,
    [3] => ICT
)

answered Oct 21, 2014 at 23:39

Dave Chen

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user1721230 · Accepted Answer · 2014-10-21 23:37:31Z

0

Figured it out, thanks if you looked:

$a1=array("Maths","English","Science","ICT");
$a2=array("Maths","ICT");

$result = array_diff($a1, $a2);

foreach ($result as $v){

$v = str_replace($result, ",,", $a1);

}
print_r($v);

answered Oct 21, 2014 at 23:37

user1721230

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3 Comments

Dave Chen Over a year ago

This won't work if you have a subject called Biochemistry and chemistry. Example.

user1721230 Over a year ago

I just encountered that exact problem with "English" and "English Lit" any ideas?

Dave Chen Over a year ago

I encourage you to take a look at my answer. It will work even if the subject contains parts of other subjects.

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