Not able to use variable i for any operation inside for loop

Question

I am new to solidity and stucked at very strange issue. I am not able to use variable i for any type of operation inside for loop.

for (uint256 i; i < data.numPoints; i++) {
        //uint256 xx = data.x; //Working
        //uint256 yy = data.y; //Working
        //uint256 xx = data.x * i; //Not working
        //uint256 yy = data.y * i; //Not working
        uint256 xx = i; //Not working
        uint256 yy = i; //Not working
        points[i] = xx;
    }

Contract get compile successfully but throw run time exception on call. Am I missing something??

Answer 1

You haven't provided enough information to replicate your issue or comment on your troubleshooting process.

It's not clear how you reached the conclusions you reached.

The line that is most suspect is the line that is not commented at all.

points[i] = xx;

If i >= points.length then this line will revert because you cannot write to an array member that doesn't exist. You can't append to an array this way.

Also, in the case that this line reverts, all previous lines will also revert because transaction execution is atomic. That can lead to confusing results using normal troubleshooting thinking.

In any case, it's impossible to say if that's the issue but it's a common issue and the other stuff appears to be low-risk.

Hope it helps.