I want to update my 'for loop'

Dear community.

I want to update my 'for loop' to get a full valid response.

for example, I want to get 5 'Space response time' regardless of some Invalid response(that didn't push space key at response phase)

so i put 'Invalid' variable to update 'TrialN', but it didn't work.

Here is my sample code.

Thanks a lot in advance for any idea...

trialtest = 5;
invalid = 0;
trialN = trialtest + invalid
spaceTime = 1.5
spaceKey    = KbName('space'); 
tflip       = [];

for T = 1: trialN
            Screen('DrawLine',w, 0, cx-10, cy, cx+10, cy, 3);
            Screen('DrawLine',w, 0, cx, cy-10, cx, cy+10, 3);
            Screen('Flip',w);
            WaitSecs(1); %초 생각해봐야 함
            Screen('FrameOval',w,0,[cx-40,cy-40,cx+40,cy+40],4);
            fixOnset = Screen('Flip',w,tflip);
            [space spaceRT] = KeyResponse(spaceTime,0,spaceKey); % wait key to continue
            mspaceRT = spaceRT*1000;
    
    if space ==1
        Screen('DrawLine',w, 0, cx-10, cy, cx+10, cy, 3);
        Screen('DrawLine',w, 0, cx, cy-10, cx, cy+10, 3);
        Screen('Flip',w);
         DrawTextUni(w,['GOOD'],'center',0,-rect(4)*.3);
    elseif space == 999 
         Screen('DrawLine',w, 0, cx-10, cy, cx+10, cy, 3);
         Screen('DrawLine',w, 0, cx, cy-10, cx, cy+10, 3);
         Screen('Flip',w);
         DrawTextUni(w,['BAD'],'center',0,-rect(4)*.3);
         invalid = invalid +1
    end
         trialN = trialtest + invalid % I put this code for update, but it doesn't work T.T
         
end

Answer 1

[Rohit Pappu]

For loop does not support dynamic update of its conditions. A better alternative would be to use while loop instead

% Initialize t
t = 1;
while(t<=trialN)
%     Block of code to be executed trialN times
    t+=1; %Increment t
end