How will iterate over a slice if that slice increases inside the loop?

When I iterate through the for loop on the slide (code below), I get the output Output: 0A,1M,2C,

code:

x := []string{"A", "B", "C"}

for i, s := range x {
	print(i, s, ",")
	x[i+1] = "M"
	x = append(x, "Z")
	x[i+1] = "Z"
}

Why is the output exactly like that and not 0A, 1Z, 2Z?

Reading the documentation, I saw that the slice is passed to the function by a pointer to the array it is based on.

Is the slice also passed to the for loop by pointer? (couldn't find why in the documentation)

If so, my guess as to why the output is exactly 0A, 1M, 2C, - because, originally, the slice was passed to the loop by pointer, and when the capacity of the slice is doubled in the first iteration of the loop, the print(i, s) values are still printed based on the base array. Is this true?

append can allocate a new array. It does. After the first append, x is now a copy and you're looping over the original. Changes to x now have no affect on s.

Let's mark up the loop with some more debugging to see.

x := []string{"A", "B", "C"}

for i, s := range x {
    fmt.Printf("Start: i=%v s=%v x=%p %v\n", i, s, x, x)
    x[i+1] = "M"
    fmt.Printf("After x[i+1] = \"M\": i=%v s=%v x=%p %v\n", i, s, x, x)
    x = append(x, "Z")
    fmt.Printf("After Append: i=%v s=%v x=%p %v\n", i, s, x, x)
    x[i+1] = "Z"
    fmt.Printf("After x[i+1] = \"Z\": i=%v s=%v x=%p %v\n\n", i, s, x, x)
}

And the result...

Start: i=0 s=A x=0xc0000161b0 [A B C]
After x[i+1] = "M": i=0 s=A x=0xc0000161b0 [A M C]
After Append: i=0 s=A x=0xc000062180 [A M C Z]
After x[i+1] = "Z": i=0 s=A x=0xc000062180 [A Z C Z]

Start: i=1 s=M x=0xc000062180 [A Z C Z]
After x[i+1] = "M": i=1 s=M x=0xc000062180 [A Z M Z]
After Append: i=1 s=M x=0xc000062180 [A Z M Z Z]
After x[i+1] = "Z": i=1 s=M x=0xc000062180 [A Z Z Z Z]

Start: i=2 s=C x=0xc000062180 [A Z Z Z Z]
After x[i+1] = "M": i=2 s=C x=0xc000062180 [A Z Z M Z]
After Append: i=2 s=C x=0xc000062180 [A Z Z M Z Z]
After x[i+1] = "Z": i=2 s=C x=0xc000062180 [A Z Z Z Z Z]

Note how after the first append the address of x changes. Any x[i+] = ?no longer affects`.