Comparison of two strings in PHP, and array_slice - php

Question

I feel like I've done something very silly, but I can't work out what it is.
I'm running through an array of arrays generated by fgetcsv(). What I want is to split the array in two at the spot where the value in one line differs from the one in the next.
This code results in $first holding all but one of the arrays, and $second holding the last - completely ignoring the string comparison. strcmp() results in the same thing.
$csv = array();
$file = fopen('A.csv', 'r');
while (($result = fgetcsv($file)) !== false)
{
$csv[] = $result;
}
fclose($file);
array_shift($csv); //gets rid of the CSV headers
$rows = count($csv);
for ($i = 0; $i <= $rows; $i++){
if ($csv[$i][1] != $csv[$i+1][1]){
$first = array_slice($csv, 0, $i);
$second = array_slice($csv, $i);
}
}
Here's an example of the CSV file:
NAME,MATCHNAME,CHROMOSOME,START LOCATION,END LOCATION,CENTIMORGANS,MATCHING SNPS
A,person_one,2,20945970,23287731,2.48,500
A,person_one,2,233444593,234432885,1.56,500
A,person_one,4,99184637,100861136,1.24,500
A,person_two,1,154990798,157871980,2.8,700 //Here's where the new array should start
A,person_two,1,67136078,70785393,2.28,800
EDIT: My expected $first for this example would be:
Array
(
[0] => Array
(
[0] => A
[1] => person_one
[2] => 2
[3] => 20945970
[4] => 23287731
[5] => 2.48
[6] => 500
)
[1] => Array
(
[0] => A
[1] => person_one
[2] => 2
[3] => 233444593
[4] => 234432885
[5] => 1.56
[6] => 500
)
[2] => Array
(
[0] => A
[1] => person_one
[2] => 4
[3] => 99184637
[4] => 100861136
[5] => 1.24
[6] => 500
)
)
And my expected $second would be:
Array
(
[0] => Array
(
[0] => A
[1] => person_two
[2] => 1
[3] => 154990798
[4] => 157871980
[5] => 2.8
[6] => 700
)
[1] => Array
(
[0] => A
[1] => person_two
[2] => 1
[3] => 67136078
[4] => 70785393
[5] => 2.28
[6] => 800
)
)

Answer 1

It is doing what you want, but when it gets to the last iteration, it compares whatever's in the last line with null, so it overwrites $first and $second.
Try adding break; after the assignments to break out of the loop when the condition is met.