Copy cells into range of cells until cell change

[Guest]

In column C is the name of an employee follwowed by lines of data for
that employee with no further data in column C until the next employee. This
sequence repeats itself for 48,000 lines.
Is there a formula/macro that will copy the employee name into the next
row of column C until the name changes and then repeat for the next name?

 

[Guest]

A brute force macro would be something like

sub nmfill()
nm=cells(1,3)
for r = 2 to 48000
if cells(r,3)="" then cells(r,3)=nm else nm = cells(r,3)
next r
end sub