Finding the first occurance of a given string

I have a large text file in which I need to find the first occurance of a given string, e.g. 'STAX'. How can I do this?

Answer 1

[KSSV]

fid = fopen('filename','r') ;
S = textscan(fid,'%s','Delimiter','\n');
S = S{1} ;
%%Get the line number of your string 'STAX'
idxS = strfind(S,'STAX');   % find the index of your string 
idx = find(not(cellfun('isempty',idxS)));  % your required indices 
S(idx)

[UWM]

Thank you very much for help :)