% while synatx: while expression, statements, end

% calculating eps

eps = 1;
while (1+eps) > 1
    eps = eps/2;
end
eps = eps*2


% example of non-evaluation of expression

A = 0;
B = 1;
while (A && B), B, end            

% example where the expression is evaluated fully
A = 1;
B = 2;
while (A || B), B, end


% multiple expressions

while (b ~= 0) && (a/b > 18.5)
if exist('myfun.m') && (myfun(x) >= y)
if iscell(A) && all(cellfun('isreal', A))

    
% Empty Arrays
% In most cases, using while on an empty array returns false. 
% There are some conditions however under which while evaluates 
% as true on an empty array. Two examples of this are

A = [];
while all(A), do_something, end
while 1|A, do_something, end

%==========================================================================

% break syntax: break
% break is not defined outside a for or while loop.

% example:

fid = fopen('fft.m','r');
s = '';
while ~feof(fid) 
   line = fgetl(fid);
   if isempty(line), break, end
   s = strvcat(s,line);
end
disp(s)


%==========================================================================

% continue syntax: continue
% continue passes control to the next iteration of the for or while loop 
%in which it appears, skipping any remaining statements in the body of the loop. 

% example:

fid = fopen('magic.m','r');
count = 0;
while ~feof(fid)
    line = fgetl(fid);
    if isempty(line) | strncmp(line,'%',1)
        continue
    end
    count = count + 1;
end
disp(sprintf('%d lines',count));