PHP - 如何使用从文本文件中获取的数字进行计算？

Question

So I have a task where I should read a text file in php, containing students IDs and their grades, separated by vertical lines. It looks something like that:

12345|4|2|1|0|4 
45678|1|2|3|4|4 
78901|5|5|5|5|4 

The program should print the amount of students there are on the file, which I managed to do by simply echoing the amount of lines. However, I should also print the sum of the grades for each student, and I simply can't find a way to do it. Do I get the characters by order on the line or something similar? I've been struggling with this for a day now and I only got as far as this:

<?php 

$file="exam.txt";
$linecount = 0;
$handle = fopen($file, "r");
while(!feof($handle)){
  $line = fgets($handle);
  $linecount++;
}


echo "total_students was $linecount:";
$homepage = file_get_contents('exam.txt');
echo $homepage;


?>

This code only prints the page and the amount of lines, nothing more.

Answer 1

So after I was guided in the right direction I managed to come up with a solution!

<?php 

$file="exam.txt";
$linecount = 0;
$handle = fopen($file, "r");
while(!feof($handle)){
  $line = fgets($handle);
  $linecount++;
}


echo "total_students was $linecount:
";


$lines = file('exam.txt');
$sum = 0 ;

foreach ($lines as $line){
$var = explode("|", $line);
$sum = $var[1]+$var[2]+$var[3]+$var[4]+$var[5];
$all += $sum;
echo "$var[0]: $sum points
";
}

$average = $all / $linecount;
echo "The average score was $average points."

?>

I exploded each line as an array divided by the "|" symbol, then I printed the student ID from the [0] of the array, and summed the rest. After that I summed the sums and thus found the average.