There is something wrong with the compiler or my understanding of Go. I have a weird bug and have whittled it down to a simple example. For some reason I can't change the array directly within a loop.
var nums [2]int
for i, v := range nums {
if i == 0 {
nums[i+1]++
} else {
fmt.Print(v)
}
}
This increments nums[1] then prints it. So it should print 1 but it prints 0.
When you use an array in an expression you get its "value" (ie, a complete new copy of the array). This includes using an array in the range expression of a loop. So when you print v you are printing the copy, but the actual nums array has been changed.
Looping on a slice instead of the array gives you what you expect:
var nums [2]int
for i, v := range nums[:] {
if i == 0 {
nums[i+1]++
} else {
fmt.Print(v)
}
}
The range creates a copy of the array (and its values), so it can iterate over them.
If you plan on mutating an array (or a slice of that matter) during iteration, it's best to reference the array/slice directly - as the v value will be a copy and in your code an old copy of the array.
So try something like:
var nums [2]int
for i := range nums {
if i == 0 {
nums[i+1]++
} else {
fmt.Print(nums[i])
}
}
make.