Changing dimnames of matrices and data frames in R

Question

Let's say I have created the following matrix:

> x <- matrix(1:20000,nrow=100)
> x[1:10,1:10]
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    1  101  201  301  401  501  601  701  801   901
 [2,]    2  102  202  302  402  502  602  702  802   902
 [3,]    3  103  203  303  403  503  603  703  803   903
 [4,]    4  104  204  304  404  504  604  704  804   904
 [5,]    5  105  205  305  405  505  605  705  805   905
 [6,]    6  106  206  306  406  506  606  706  806   906
 [7,]    7  107  207  307  407  507  607  707  807   907
 [8,]    8  108  208  308  408  508  608  708  808   908
 [9,]    9  109  209  309  409  509  609  709  809   909
[10,]   10  110  210  310  410  510  610  710  810   910

What are the methods in R to change row and column names? For example, I like row names to be SS1, SS2, ..., SS100 and column names to be M1, M2, ..., M200. I usually work with data with 1000s of rows and columns, and I need a good method to do that. Some people use something like attributes(x)$dimnames <- list(...) and some use rownames <- paste(...). What are all possible methods?

My second question is, can I use the same methods after I convert the matrix to a data frame?

Answer 1

From comment to answer:

row.names(x) <- paste("SS", 1:nrow(x), sep="")
colnames(x) <-  paste("M" , 1:ncol(x), sep="")

As @doug wrote, it works for matrices and data frames.