kotlin fun with string concatenation - function

Question

I need help concatenating a string in a kotlin viewmodel. I am trying to return what the code should print to the status text view. The formula determines from a Int what the status should be then outputs a message to the User. I am unsure as to what method should be used to create a string that I wanted to return.
fun formula(f: Int, b: Int, l: Int, d: Int) : String {
if (f > 70 && f < 99) {
val ftxt = "Normal"
} else if (f < 71) {
val ftxt = "Hypoglycemic"
}
if (b > 140) {
val btxt = "Abnormal"
} else if (b < 71) {
val btxt = "Hypoglycemic"
}
if (l > 140) {
val ltxt = "Abnormal"
} else if (l < 71) {
val ltxt = "Hypoglycemic"
}
if (d > 140) {
val dtxt = "Abnormal"
}else if (d < 71) {
val dtxt = "Hypoglycemic"
}
else {
val ftxt = "Abnormal"
val btxt = "Normal"
val ltxt = "Normal"
val dtxt = "Normal"
}
var status = calendar.toString()
status += "\n Fasting: "
status += ftxt + "\n Breakfast: "
status += btxt + "\n Lunch: "
status += ltxt + "\n Dinner: " + dtxt
return status
}

Answer 1

Without entering into detail on how you could improve your function you're having the "red squiggles" because those val are declared within the scope of the if-else blocks.
You can declare them out of the block and assign values:
fun formula(f: Int, b: Int, l: Int, d: Int) : String {
var ftxt = ""
var btxt = ""
var ltxt = ""
var dtxt = ""
if (f > 70 && f < 99) {
ftxt = "Normal"
} else if (f < 71) {
ftxt = "Hypoglycemic"
}
if (b > 140) {
btxt = "Abnormal"
} else if (b < 71) {
btxt = "Hypoglycemic"
}
if (l > 140) {
ltxt = "Abnormal"
} else if (l < 71) {
ltxt = "Hypoglycemic"
}
if (d > 140) {
dtxt = "Abnormal"
}else if (d < 71) {
dtxt = "Hypoglycemic"
}
else {
ftxt = "Abnormal"
btxt = "Normal"
ltxt = "Normal"
dtxt = "Normal"
}
var status = calendar.toString()
status += "\n Fasting: "
status += ftxt + "\n Breakfast: "
status += btxt + "\n Lunch: "
status += ltxt + "\n Dinner: " + dtxt
return status
}