using a while loop to add one to a vector

I am supposed to use a while loop to add one to a vector. when i use this code it goes on for infinity but my bounds are set for when i is less than or equal to the length of the vector.

function [vec] = addOne(vec)
vec = [2 1 5 2]
l = length(vec)
i  = 1:l
while i <= l
    vec(i) = vec(i)+1
end
addOne = vec;
end

Answer 1

[David Hill]

function vec = addOne(vec)
i=1;
while i<=length(vec)
    vec(i) = vec(i)+1;
    i=i+1;
end
end