# V7037\. The nested loop counter is initialized with the outer loop counter\.

The analyzer has detected a nested for loop whose counter is initialized with the value of the outer loop's counter\. Such code often contains a bug: most likely, the iteration should start from the next element, i \+ 1\.

The example:

```cpp
function hasDuplicates(arr) {
  for (let i = 0; i < arr.length; i++) {
    for (let j = i; j < arr.length; j++) {
      if (arr[i] === arr[j])
        return true;
    }
  }
  return false;
}
```

The function should check whether an array contains duplicate elements, but because the inner loop that starts with `j = i`, each element is compared with itself on the first iteration\. Since `arr[i] === arr[i]` is always `true`, the function returns `true` for any non\-empty array\.

The fixed code:

```cpp
function hasDuplicates(arr) {
  for (let i = 0; i < arr.length; i++) {
    for (let j = i + 1; j < arr.length; j++) {
      if (arr[i] === arr[j])
        return true;
    }
  }
  return false;
}
```

The analyzer also issues a warning:

```cpp
function hasDuplicates(arr) {
  for (let i = 0; i < arr.length; i++) {
    for (let j = i; j < arr.length; j++) {
      if (i !== j && arr[i] === arr[j])
        return true;
    }
  }
  return false;
}
```

In this case, the `i !== j` is checked on every iteration, even though it only filters out a single one\. The extra iteration is redundant, and the extra branch complicates loop optimization for the compiler\.