Formatting fwrite output to a external file - Implode Error - php

Question

The code I am working on queries a database through php and then placed the results into an array called CS. This array is then encoded so it can work with javascript. It is then supposed to edit the output so there is a newline after every row. The latter is where I have the problem. I get implode: invalid arguments passed every time regardless of how I edit the implode function.
Here is the code:
<?php
$servername = "*****";
$username = "****"; --> edited for privacy.
$password = "*******";
$database = "********";
// Create connection
$conn = new mysqli($servername, $username, $password, $database);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
// sql statement for tables and naming array to hold it in
$sql = "SELECT COURSE_ID FROM cs";
$result = $conn->query($sql);
$CS = array();
if ($result->num_rows > 0) {
// fill array with results
while($row = $result->fetch_assoc()) {
array_push($CS, $row);
}
} else {
echo "0 Results";
}
// encodes php array so it can be used in javascript
$json_array = json_encode($CS);
$conn->close();
// fills Computer_Science.js with the contents of the json_array and adds new lines in between
$json_array_lines = implode($json_array, "/n"); --> this line
$fp = fopen('..\js\DegreePlans\Computer_Science.js', 'w');
fwrite($fp, print_r($json_array_lines, TRUE));
fclose($fp);
?>
I'm at a loss on how to fix the error. Any help given will be appreciated.

Answer 1

I fixed it!
<?php
$servername = "*****";
$username = "****"; --> edited for privacy.
$password = "*******";
$database = "********";
// Create connection
$conn = new mysqli($servername, $username, $password, $database);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
// sql statement for tables and naming array to hold it in
$sql = "SELECT COURSE_ID FROM cs";
$result = $conn->query($sql);
$CS = array();
if ($result->num_rows > 0) {
// fill array with results
while($row = $result->fetch_assoc()) {
array_push($CS, $row);
}
} else {
echo "0 Results";
}
$conn->close();
//encode the array so it can be used in javascript and use regular expressions to format it.
$json_string = json_encode($CS);
$re = "/.,/";
$subst = "},\r\n"; --> right here!
$json_string = preg_replace($re, $subst, $json_string);
$fp = fopen('..\js\DegreePlans\Computer_Science.js', 'w');
fwrite($fp, print_r($json_string, TRUE));
fclose($fp);
?>