Working with text-files in PHP - php

Question

As mentioned before, I am a beginner when it comes to PHP coding. I have made a text file which has my students information, as per below - this includes their name, marks for subjects, e-mail address and date of registration:
Ann Thompson : 50,90,82,64,75 : ann#amuniversity.com: 2016-02-01
Jeremiah Hanson: 80, 75, 88 : jeremiah#amuniversity.com: 2016-03-02
Billy Jones: 89, 72, 46, 54 : billy#amuniversity.com: 2016-04-12
and I have also made a form which inputs a field which takes in the filename which the user wishes to read from and a field for the filename which the user wishes to write to.
Where do I start to get the output below?
Summary for students:
Ann Thompson enrolled in 2016-02-01, has an average of 48, with a symbol F.
Jeremiah Hanson enrolled in ....
Billy Jones enrolled in ....
It should also show the date at the bottom when it was last modified.
Please kindly help

Answer 1

Please check the following code. I commented on the code wherever I thought needed. Let me know if you don't understand something from it. And obviously, you need to update the checkGrade function as per your grade system, but you get the idea :)
<?php
// Read the input file line by line into "input" array
$filename = "input.txt";
$input = explode("\n", file_get_contents($filename));
// Go through each line
for($i = 0; $i < sizeOf($input); $i++){
// split line by :
$line = explode(":", $input[$i]);
// Initialize variables based on position
$name = $line[0];
$numbers = $line[1];
$email = $line[2];
$registration = $line[3];
// Calculate average
// Remove any spaces first from the numbers
$numbers = str_replace(' ', '', $numbers);
// Split the numbers by ,
$numbersArray = explode(",", $numbers);
$sum = 0;
// Calculate sum
for($j = 0; $j < sizeOf($numbersArray); $j++){
$num = (int)$numbersArray[$j];
$sum += $num;
}
$avg = $sum/sizeof($numbersArray);
// Print it
echo "$name enrolled in $registration, has an average of $avg, with a symbol ". checkGrade($avg) ."<br>";
}
// Last modified date of the input file
echo "<br><br><br>";
if (file_exists($filename)) {
echo "This file was last modified: " . date ("F d Y H:i:s.", filemtime($filename));
}
function checkGrade($num){
if ($num < 65){
$grad = 'F';
}
else if ($num<= 66 && $num >=65){
$grad = 'D';
}
else if ($num <= 69 && $num >=67){
$grad = 'D+';
}
else if ($num <= 73 && $num >=70){
$grad = 'C-';
}
else if ($num <= 76 && $num >=74){
$grad = 'C';
}
else if ($num<= 79 && $num >=77 ){
$grad = 'C+';
}
else if ($num <= 83 && $num >=80){
$grad = 'B-';
}
else if ($num <= 86 && $num >=84){
$grad = 'B';
}
else if ($num <= 89 && $num >=87){
$grad = 'B+';
}
else if ($num <= 93 && $num >=90){
$grad = 'A-';
}
else if ($num <= 96 && $num >=94){
$grad = 'A';
}
else if ($num >= 97){
$grad = 'A+';
}
return $grad;
}
?>
Here is the output:
Ann Thompson enrolled in 2016-02-01, has an average of 72.2, with a symbol C-
Jeremiah Hanson enrolled in 2016-03-02, has an average of 81, with a symbol B-
Billy Jones enrolled in 2016-04-12, has an average of 65.25, with a symbol D
This file was last modified: May 03 2017 13:12:13.