Default value of a text field based on radio selection - PHP if - php

Question

I need to change the value of a text field (Agerisk2) to a number based on the selection of a radio field (Age)
In the text field additional attributes I have
onChange="$Agerisk2"
In the text field default value I have:
//<code>
$Age = [];
$Agerisk2 = null;
switch ($Age) {
case $Age "Under 45 years":
$Agerisk2 = "0";
break;
case $Age "45 – 54 years":
$Agerisk2 = "2";
break;
case $Age "55 – 64 years":
$Agerisk2 = "3";
break;
case $Age "64 years or over":
$Agerisk2 = "4";
break;
default:
$Agerisk2 = null;
break;
}
//</code>
Something isn't quite right and I'd really appreciate some help. Thank you

Answer 1

Your switch statement is invalid. Better use match for it.
Also note your variable naming should match the PSR
$age = 47;
$ageRisk = match (true) {
$age < 45 => 0,
$age >= 45 && $age <= 54 => 2,
$age >= 55 && $age <= 64 => 3,
$age >= 64 => 4,
default => null
};
echo $ageRisk;
prints
2
If you are below PHP 8 you can fallback to switch, which does not look so nice.
switch (true) {
case $age < 45:
$ageRisk = 0;
break;
case $age >= 45 && $age <= 54:
$ageRisk = 2;
break;
case $age >= 55 && $age <= 64:
$ageRisk = 3;
break;
case $age >= 64:
$ageRisk = 4;
break;
default:
$ageRisk = null;
break;
}