In C++, I need a custom iterator that goes over an array, not all elements of which are marked as valid. Thus, the next() function must be a bit smarter than the one just doing ++iterator; I need it to check validity of the next element, skip it if not valid, and so forth till a valid element is found or encoutering the array end. Just wonder if there’s a more elegant way to do so, rather than checking all elements in a loop one by one. For example:

struct MyDataType {
    // ...
    bool _flagValid;
    // ...

    bool is_valid() { return _flagValid; }
};

MyDataType DataArray[DATA_ARRAY_SIZE];
// ...
uint32_t count_valid_ones () {
    auto cout = 0U;
    for (auto &d: DataArray) {
        if (d.is_valid) count++;
    }
    return count;
}

But this way woud be preferable:

uint32_t count_valid_ones () {
    auto cout = 0U;
    auto __range = ValidOnesOnly(DataArray)
    for (auto &d: __range) count++;
    return count;
}