PHP: Array to string conversion when retrieving outside function - php

Question

Good day!
I have a problem here that I can't solve (last 5hrs).
here's my codes:
include 'assets\function\retrieveFunction.php';
$loadGradProgram = array();
$x = count(getCourseInfo());
for($i=0;$i<=$x;$i++){
$loadGradProgram[$i] = getCourseInfo();
}
echo $loadGradProgram[0];
getCourseInfo function
Solution 1:
function getCourseInfo(){
$getInfo = array();
include 'assets\database\connect.php';
$i = 0;
$x = 0;
$sql = "SELECT c.courseID, c.courseCode, c.courseTitle, m.description";
$sql .=" FROM tblcourse as c INNER JOIN tblcoursemajor as m ON c.courseid=m.courseID ORDER BY c.courseID";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$getInfo[$i] = $row;
$i++;
}
return $getInfo;
}
}
Result: Array to string conversion
Solution 2:
function getCourseInfo(){
$getInfo = array();
$loadInfo = array();
include 'assets\database\connect.php';
$i = 0;
$x = 0;
$sql = "SELECT c.courseID, c.courseCode, c.courseTitle, m.description";
$sql .=" FROM tblcourse as c INNER JOIN tblcoursemajor as m ON c.courseid=m.courseID ORDER BY c.courseID";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$getInfo[$i] = $row;
$i++;
}
$conn->close();
for($x,$x<=$i;$x++;){
$loadInfo[] = implode(',', $getInfo[$x]);
}
return $loadInfo;
}
}
Result: Still the same
and this line causing error: echo $loadGradProgram[0];
I use echo just to see if the query is working.

Answer 1

if you want a multi-dimmentional array like in w3c documentation, you do it like this :
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$getInfo[$i][] = $row['courseID'];
$getInfo[$i][] = $row['courseCode'];
...
$i++;
}
return $getInfo;
then, if you want to diplay an information in the array you can do a foreach loop or a for loop like :
foreach($loadGradProgram as $key => $value) // here the key is useless
{
echo $value[0];
echo $value[1];
}
or directly like this :
echo $loadGradProgram[0][0];
echo $loadGradProgram[0][1];
echo $loadGradProgram[1][0];