ChatGPT says this and I agree.
Both options are technically correct and will have the same effect since sizeof(TableCol) and sizeof(LVCOLUMNW) are equivalent.
However, using sizeof(TableCol) is generally preferred because it directly ties the memset operation to the actual variable you're working with. This approach improves code maintainability. If the type of TableCol ever changes, the code will still work correctly without needing to update the memset call.
So, while both are okay, using sizeof(TableCol) is often considered better practice.