you can use find e.g.
find(A(:,1)==B(1) & A(:,2)==B(2) & A(:,3)==B(3))
will give the index of the string \ rows that matches.
Try using matlab reading, that's all ...
By the way, an alternative is to use ismember :
[~,id]=ismember(B,A,'rows')
the id variable will give the index of the rows where B matches A
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