Scala Compilation Error : Value += is not member of Int - scala

Question

I am at a beginner level in Scala, I am trying the following code:
var i: Int = 0
for (i <- 0 to 10) {
if (i == 2) {
i += 1
}
println(i)
}
When I increment i the compiler says Value += is not member of Int.

Answer 1

You're declaring i twice, one at the outer scope and one in the inner. Your for comprehension looks at the inner i, which is a val, not a var, thus shadowing the external declaration.
Bind to a different name:
var counter: Int = 0
for (i <- 0 to 10) {
if (i == 2) {
counter += 1
}
println(counter)
}
Note you can do this without declaring an outer variable at all, using count:
val count = (0 to 10).count(i => i == 2)
println(count)
Edit:
From your comments, I understand you want to print all numbers other than 2. For that you need to negate your condition:
if (i != 2) {
counter += 1
}
Or if you just want to filter out 2:
(0 to 10).filter(_ != 2).foreach(println)
Edit 2:
From you comments, it looks like a while loop is better for what you're trying to achieve:
var i = 0
while (i < fruits.length) {
if (fruits(i) == "Banana") {
i += 1
println(i + " " + fruits(i))
} else if (fruits(i) == "Orange") {
i += 1
println(i + " " + fruits(i))
}
}
But this code will run into an infinite loop since you're only incrementing i if the conditions are met. Other than that, since your doing i + 1, you might be going out of bounds if the last element equals "Banana" or "Orange", so you might want to rethink what you're doing. You'll probably run into an

Answer 2

As mentioned in Yuval's answer, you're declaring i twice. Not only that, but the inner one is implicitly immutable, therefore making it impossible for you to mutate it (that's why you get a compilation error).
To achieve the same effect you get from mutation you can use a guard in the for comprehension, like this:
for (i <- 0 to 10 if i != 2) {
println(i)
}
This code can be seamlessly translated (and that's what the compiler actually does) to the following
(0 to 10).withFilter(i => i != 2).foreach(i => println(i))

Answer 3

The new error mentioned in the comment looks like:
scala> :pa
// Entering paste mode (ctrl-D to finish)
var i: Int = 0
for(i <- 0 to 10)
{
if (i == 2)
{
i += 1
}
println(i)
}
// Exiting paste mode, now interpreting.
<pastie>:19: error: value += is not a member of Int
Expression does not convert to assignment because receiver is not assignable.
i += 1
^
It should say i instead of receiver for the simple case, where the LHS is not a complex expression, but you get the idea.
Also, nobody mentioned this:
scala> :pa
// Entering paste mode (ctrl-D to finish)
object X {
var i: Int = 0
for(i <- 0 to 10)
{
if (i == 2)
{
this.i += 1
}
println(this.i)
}}
// Exiting paste mode, now interpreting.
defined object X
scala> X
0
0
1
1
1
1
1
1
1
1
1
res3: X.type = X$#1129829c