Process a list with a loop, taking 100 elements each time and automatically less than 100 at the end of the list

You can make use of LINQ Skip and Take and your code will be cleaner.

for (int i = 0; i < listLength; i=i+100)
{
    var items = bigList.Skip(i).Take(100); 
    // Do something with 100 or remaining items
}

Note: If the items are less than 100 Take would give you the remaining ones.