Compare an array based on previous value of the array - php

Question

I have an array that looks like this:
Array (
[0] => Array (
[START] => COI-COK
[RETURN] => CAI - DEL
)
[1] => Array (
[START] => COK - AMM
[RETURN] => CAI - DEL
)
)
I want to check if both 'start' and 'end' values of previous and current array are same or not. If not then, print some value. How can I do it?
This is my attempt:
foreach($data as $datas)
{
$old_start = $datas['START'];
$old_return = $datas['RETURN'];
...
if( ($old_start == $datas['START']) && ($old_return == $datas['RETURN']))
{
}
else
{
}
}
But it didn't work because all the time old_start value will be equal to $datas['START'].
print_r($data) shows this output:
Array (
[0] => Array (
[Sl] => 2
[TRAVELDAY] => 2015-11-11
[RETURNDAY] => 2015-11-27
[START] => COI-COK
[RETURN] => CAI - DEL
)
[1] => Array (
[Sl] => 1
[TRAVELDAY] => 2015-11-11
[RETURNDAY] => 2015-11-27
[START] => COK - AMM
[RETURN] => CAI - DEL
)
)

Answer 1

You have to put the assignment after the comparison, not before:
$old_start = '';
$old_return = '';
foreach($data as $datas)
{
//....
if($old_start=='' || $old_start == $datas['START'] && $old_return == $datas['RETURN'])
{
//....
}
else
{
//code to be executed
}
$old_start = $datas['START'];
$old_return = $datas['RETURN'];
}

Answer 2

Try like this..
$old_start = "";
$old_return = "";
foreach($data as $datas)
{
if( ($old_start == $datas['START']) && ($old_return == $datas['RETURN']))
{
//true code to be executed
}
else
{
//false code to be executed
}
$old_start = $datas['START'];
$old_return = $datas['RETURN'];
}

Answer 3

foreach($data as $sample) {
if (!isset($temp)) {
$temp = $sample;
} else {
if ($temp['START']==$sample['START'] && $temp['RETURN']==$sample['RETURN']) {
; //WHATEVER EQUAL
} else {
; //WHATEVER NOT EQUAL
}
$temp = $sample;
}
}

Answer 4

$array = Array ( 0 => Array ( "START" => "COI-COK", "RETURN" => "CAI - DEL"), 1 => Array ( "START" => "COK - AMM","RETURN" => "CAI - DEL" ),2=> Array ( "START" => "COK - AMM","RETURN" => "CAI - DEL" ) );
$old_start = "";
$old_return = "";
foreach($array as $ak=>$av){
if(empty($old_start)){
$old_start = $av['START'];
$old_return = $av['RETURN'];
}else{
if($old_start == $av['START'] && $old_return == $av['RETURN']){
echo "SAME\n";
}else{
echo "Varies\n";
}
$old_start = $av['START'];
$old_return = $av['RETURN'];
}
}
//Output
Varies //key 1 will not match with key 0 value
Same // key 2 will not match with key 1 value
Hope this clears your logic, add as many array value you want , I modified your array from 2 to 3 to show the difference. This will compare n with n+1 and show the result.