Matlab 2010a

Hi,

Does anyone know how to take input of a *.dat file in Matlab 2010a?
lets say i have a csv file of 4rows and 4 colums. and just want to read the values.
%initialize a matrix
B= zeros( 4,4 );
prompt={'Enter your file name with extention:'};
answer=inputdlg(prompt);
fid = fopen(answer);
count = 0;
while ~fopen(fid)
{loop to read the contents of the file name i entered in answer}

but it dosent work.

Can anyone please help?

Regards
matlab81