This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
If you don't want to use another array, and you don't want empty array positions, what do you think your other options are? You could shift everything down an index, but then you'd still have empty array positions at the end of the array. Are you sure you're understanding your requirements correctly?