Repeat an iteration after verifying an if statement

I have a while loop with 'i' going from 1 to 50. Inside the while loop, I have an if condition, which if it is true, should rerun that iteration. A simple example would be this:

 i=1;
num = zeros(50,1);
while i<50
num(i) = randi(100);
if num(i)>70
%code to rerun this iteration
end
end

Suppose I get num(40) = 89. I want the iteration with i=40 to run again, so that num(40) gets a different value. I want the while loop to not increment 'i' if the 'if' condition is true. How should I do this? I tried i = i - 1, so that it would add 1 for the increment. But the increment doesn't happen, and i goes to negative values.

[Tejas Adsul]

Oh! While loop doesn't automatically increment 'i'. We have to type it at the end of the iteration code. Got it! I can just skip the increment line if the condition is true.