Binding parameters in switch statement - php

Question

I need a little helping hand in my script. As the title suggests it's about parameters. I have this code:
if (isset($_GET['sendit'])) {
$theusersname = $_GET['theusersname'];
$totalmarks = $_GET['totalmarks'];
$mathsobt = $_GET['mathsobt'];
$physicsobt = $_GET['physicsobt'];
$chemistryobt = $_GET['chemistryobt'];
$computerobt = $_GET['computerobt'];
$englishobt = $_GET['englishobt'];
$totalobt = $mathsobt + $physicsobt + $chemistryobt + $computerobt + $englishobt;
$modulo = ($totalobt / $totalmarks) * 100;
$grade = "";
//for grades
switch ($modulo, $grade) {
case 'A-1'://100% ro 80%
if ($modulo >= 79.5 && $modulo <= 100){
$grade = "A-1";
}
break;
case 'A'://79% to 70%
if ($modulo >= 69.5 && $modulo <= 79.4) {
$grade = "A";
}
break;
case 'B'://69 to 60
if ($modulo >= 59.5 && $modulo <= 69.4){
$grade = "B";
}
break;
case 'C'://59 to 50
if ($modulo >= 49.5 && $modulo <= 59.4){
$grade = "C";
}
break;
case 'D'://49 to 40
if ($modulo >= 39.5 && $modulo <= 49.4){
$grade = "D";
}
break;
case 'F'://32 to rest
if ($modulo >= 33 && $modulo <= 39.4){
$grade = "F";
}
default:
if ($modulo >= 0 && $modulo <= 32.9){
$grade = "N/A";
}
break;
}
//for remarks
switch ($grade) {
case '':
break;
default:
break;
}
$query = "INSERT INTO `report`(`name`, `grade`, `total`, `mathsobt`, `physicsobt`, `chemistryobt`, `computerobt`, `englishobt`, `totalobt`, `modulo`, `remarks`) VALUES ('$theusersname', '$grade', '$totalmarks', '$mathsobt', '$physicsobt', '$chemistryobt', '$computerobt', '$englishobt', '$totalobt', '$modulo', '$remarks')";
$result = mysqli_query($mysqliConn, $query);
// if (mysqli_query($mysqliConn, $query)) {
// echo "New record created successfully";
// } else {
// echo "Error: " . $query . "<br>" . mysqli_error($mysqliConn);
$mysqliConn->close();
// }
The grading switch statement doesn't work. Because I just can't get what parameter I need to give. Same goes for the remarks too. The code may be terrible and don't have sanitization (which in this case I don't need). I'm also a little bit confuse with the strings I passed for cases. I mean does it have an effect on overall?
Thank you.
PS: If there is already a similar answer out there, which i unfortunately i didn't find, i'm ready to view the link. Please post a little explanatory comment.

Answer 1

$modulo && $grade is a boolean expression. Its value is either TRUE or FALSE (and not 'A', 'B' or 'C').
But PHP is a loose-type language and it changes the types of its values as needed before using them. Because of this, 'A' == TRUE and '' == FALSE and your code produces only 'A-1' and 'N/A' grades.
A switch doesn't help here. You should use a sequence of cascaded ifs:
if ($modulo >= 79.5) {
$grade = "A-1";
} elseif ($modulo >= 69.5) {
$grade = "A";
} elseif ($modulo >= 59.5) {
$grade = "B";
} elseif ($modulo >= 49.5) {
$grade = "C";
} elseif ($modulo >= 39.5) {
$grade = "D";
} elseif ($modulo >= 33) {
$grade = "F";
} else {
$grade = "N/A";
}
Read how PHP compare values of different types and read how the switch control structure works.

Answer 2

Here you go
$theusersname = 'theusersname';
$totalmarks = 500;
$mathsobt = 87;
$physicsobt = 82;
$chemistryobt = 75;
$computerobt = 79;
$englishobt = 91;
$totalobt = $mathsobt + $physicsobt + $chemistryobt + $computerobt + $englishobt;
$modulo = ($totalobt / $totalmarks) * 100;
switch ($modulo) {
case $modulo >= 33 && $modulo < 39.5:
$grade = "F";
break;
case $modulo >= 39.5 && $modulo < 49.5:
$grade = "D";
break;
case $modulo >= 49.5 && $modulo < 59.5:
$grade = "C";
break;
case $modulo >= 59.5 && $modulo < 69.5:
$grade = "B";
break;
case $modulo >= 69.5 && $modulo < 79.5:
$grade = "A";
break;
case ($modulo >= 79.5 && $modulo <= 100 ):
$grade = "A-1";
break;
default:
$grade = "N/A";
break;
}
switch ($grade) {
case 'A-1':
$remarks = "You have got A-1 ";
break;
case 'A':
$remarks = "You have got A ";
break;
case 'B':
$remarks = "You have got B ";
break;
case 'C':
$remarks = "You have got C ";
break;
case 'D':
$remarks = "You have got D ";
break;
case 'F':
$remarks = "You have got F ";
break;
default:
$remarks = "You have got nothing";
break;
}
echo $query = "INSERT INTO `report`
(`name`, `grade`, `total`, `mathsobt`, `physicsobt`,
`chemistryobt`, `computerobt`, `englishobt`, `totalobt`,
`modulo`, `remarks`)
VALUES ('$theusersname', '$grade', '$totalmarks', '$mathsobt',
'$physicsobt', '$chemistryobt', '$computerobt', '$englishobt',
'$totalobt', '$modulo', '$remarks')";
OUTPUT
INSERT INTO `report`
(`name`, `grade`, `total`, `mathsobt`, `physicsobt`,
`chemistryobt`, `computerobt`, `englishobt`, `totalobt`,
`modulo`, `remarks`)
VALUES ('theusersname', 'A-1', '500', '87', '82', '75', '79',
'91', '414', '82.8', 'You have got A-1 ')