How come cp still in interactive mode when overiding

When you use the command cp -f -r /somedirectory. Somehow there is still a prompt when you overide. Theoretically, cp -f will overide the interactive mode but somehow it did not.

When it happened, do look at your .bashrc where you have a line

alias cp='cp -i'

This may have caused interactive mode not to be over-written by "cp -f"