Similar code as vec2ind function for MATLAB coder?

Hi

I want a code that give similar function as vec2ind.

I found this code sum( repmat((1:size(vec,1)).', 1, size(vec,2)) .* vec)

but this code doesn't give same result as vec2ind

for example vec= [1;0;1;0;1;1;5;0]

The result of vec2ind is 7.

The result of sum( repmat((1:size(vec,1)).', 1, size(vec,2)) .* vec) is 50.

How can get exactly same result?. I want to transfer This matlab code to c++.

Thank you.