How can I check that multiple cells have the same string?

[jnathan]

I want to check if cells C1, D1 and E1 contain the same name. For example if the cells all contain the 'Joe Bloggs' (or whatever the name variable happens to be) then cell F1 should say "Yes", else "No".

Anyone out there who can help? Much appreciated!

 

[MisterBates]

=if(and(C1=D1,D1=E1),"yes","no")