I am trying to check if a value of a vector is equal, but it is a word not a number. how can I do that?

Hi,

I have a vector >> t = {'add','23','27','pow','3','2','2','stop','4','stop', ...

% 'mult','add','2','3','stop','add','4','5','stop','stop', ...

% 'div','2','3','4','stop', ...

% 'sub','4','2','stop', ...

% 'mult','2','3','div','2','stop','add','4','5','2', ...

% 'mult','1','3','stop','stop','3','stop'}

and I am trying to set an if condition for when t(x)= 'stop' but I keep getting an error that says Undefined operator '==' for input arguments of type 'cell'. If you could tell\help me with how to do this I would greatly appreciate it!

Answer 1

[Geoff Hayes]

Ashley - how are you iterating over your cell array? It looks like all of your elements are strings (character arrays) so you should be using either strcmp or strcmpi to compare two strings. For example,

k = 2;
if strcmp(t{k}, 'stop')
    % do something
end

If you use == you can get errors when the two strings that you are comparing are of different dimension.

[Ashley Nelson]

this is currently what I have for it:

function [expo] = doPow ( expr, pos )
   expo = 1;
   l=length(expo)
   a=zeros(1,l)
   for i=pos:l
       if expr(i)= stop
           a(1,i)=i
       
       else 
           a(1,i)=0
       end
   end

[Ashley Nelson]

obviously the expr(i)=stop is where I'm having issues, because I need to know the value of i where expr is equal to stop

[Geoff Hayes]

Ashley - try using strcmp....it looks like you are using = (assignment) instead which will not work...and you must wrap your string in single quotes. Consider

if strcmp(expr{i}, 'stop')

Note how we use the {} to access the element in the cell array (I'm assuming this is still the case?).

[Ashley Nelson]

it works! thanks!