how can I find the values 88,89,90 and replace them as 65,66,67 using a for loop?

Generator = randi([65,90],[1,10])

Answer 1

[Walter Roberson]

Generator = randi([65,90],[1,10])

for K = 1 : numel(Generator)
    if Generator(K) == 88
        Generator(K) = 65;
    elseif Generator(K) == 89
        Generator(K) = 66;
    elseif Generator(K) == 90;
        Generator(K) = 67;
    end
end

This is deliberately clumsy -- if you have a requirement to use a for loop instead of something more efficient, then who-ever imposed the requirement to use a for loop probably wants to see the steps spelled out.