Compare array in loop

Question

I have 2 arrays with different sizes, in some cases one array can have more elements than the other array. However, I always need to compare the arrays using the same id. I need to get the other value with the same id in the other array

I have tried this, but the problem happens when I compare the two arrays in a loop when the other array has more elements than one, because duplicate the loop and data , and it does not work.

Here is what I've tried:

<?php
/// Actual Data Arrays ///
$data_1=array("a1-fruits","b1-apple","c1-banana","d1-chocolate","e1-pear");
$data_2=array("b1-cars","e1-eggs");
///

for ($i=0;$i<count($data_1);$i++)
{

/// Explode ID $data_1 ///
$exp_id=explode("-",$data_1[$i]);   
///

for ($h=0;$h<count($data_2);$h++)
{

/// Explode ID $data_2 ///  
$exp_id2=explode("-",$data_2[$h]);
///

if ($exp_id[0]=="".$exp_id2[0]."")
{
print "".$data_2[$h]."";
print "<br>";
}
else
{
print "".$data_1[$i]."";
print "<br>";   
}

/// 
}
///

}
?>

I want the following values :

"a1-fruits"
"b1-cars"
"c1-banana"
"d1-chocolate"
"e1-eggs"

Yet, I get this (which isn't what I want):

a1-fruits
a1-fruits
b1-cars
b1-apple
c1-banana
c1-banana
d1-chocolate
d1-chocolate
e1-pear
e1-eggs

I tried everything I know and try to understand how I can do this because I don't understand how to compare these two arrays. The other problem is when one size has more elements than the other, the comparison always gives an error.

I FIND THE SOLUTION TO THIS AND WORKING IN ALL :

<?php
/// Actual Data Arrays ///
$data_1=array("a1-fruits","b1-apple","c1-banana","d1-chocolate","e1-pear");
$data_2=array("b1-cars","e1-eggs","d1-chocolate2");
///



for ($i=0;$i<count($data_1);$i++)
{
$show="bad";    
/// Explode ID $data_1 ///
$exp_id=explode("-",$data_1[$i]);   
///

for ($h=0;$h<count($data_2);$h++)
{
/// Explode ID $data_2 ///  
$exp_id2=explode("-",$data_2[$h]);
///
if ($exp_id2[0]=="".$exp_id[0]."")
{
$show="ok"; 
print "".$data_2[$h]."<br>";
}
/// 
}

if ($show=="bad")
{
print "".$data_1[$i]."";
print "<br>";
}

///

}
?>

Community · Accepted Answer · 2023-11-17 20:07:23Z

2

Th problem with your loop is, you are comparing and printing at the same time. So what happens is this:

  loop 1 : a1
    loop 2: b1 - compare
            b1 - print $exp_id[0] or $exp_id2[0]
    loop 2: e1 - compare
            e1 - print $exp_id[0] or $exp_id2[0]
  loop 1 : b1
    loop 2: b1 - compare
            b1 - print $exp_id[0] or $exp_id21[0]
    loop 2: e1 - compare
            e1 - print $exp_id[0] or $exp_id2[0]

   and so on

You will notice that if you add another element to $data_2, you will print 3 of each. You first have to store them somewhere, and print them later.

think you have to create two new arrays, containing key-value pairs, and then just merge them. PHP's array_merge will always take the value from the second array if the key already exists. Then you can put them back togheter;

So:

$data_1=array("a1-fruits","b1-apple","c1-banana","d1-chocolate","e1-pear");
$data_2=array("b1-cars","e1-eggs");

$tmp_1=array();
$tmp_2=array();
$result=array();

foreach($data_1 as $value){$t=explode('-',$value);$tmp_1[$t[0]]=$t[1];}
foreach($data_2 as $value){$t=explode('-',$value);$tmp_2[$t[0]]=$t[1];}

$merge=array_merge($tmp_1,$tmp_2);

foreach($merge as $key=>$value)$result[]=$key.'-'.$value;

edited Nov 17, 2023 at 20:07

CommunityBot

11 silver badge

answered Jun 1, 2014 at 8:33

Michel

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7 Comments

user3626084 Over a year ago

why you put until $tmp_1=array(); $tmp_2=array(); $result=array();

Michel Over a year ago

To initialize the arrays. But it isn't strictly nessecary.

user3626084 Over a year ago

And no possible do this in the loop without use array_merge ?

Michel Over a year ago

Of course you can, but why would you? Now PHP takes care of all the comparing.

user3626084 Over a year ago

I like know how operate inside loop for learn about this method , always i want understand how control data inside loop , and no get learn this well , by this i like how control in loop

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