while loops with and conditions (repeat until conditions are met)

Hello everyone

I'm not the best in coding but i'm trying hard. So basically, i need a code where i can prompt the user to enter any random, real, and positive value only.(number of values must be EVEN).

For example:

the user would enter: 1 4 5

the output would be: re-enter your values as their number must be even

the user would re-enter: 1 4 5 3

and the loop will continue in this case

I hope you got my point and could assist me hence i'm really struggling and haven't got much time

[Alex Mcaulley]

What have you tried? Can you show your code?

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

Hint: length() and mod()

[Mehmed Saad]

if user is going to eneter like

1 4 5

in that case you have to use input('prompt','s')

[Mariam Al Zarouni]

So basically i've tried many codes.

First code: ( the user enters two values only, values should be real)

the problem with this code is that i get ability to type in my input but when i press enter afterwards, i get this red long message saying "Error: Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses."

Resistor=input('Enter values [R1...Rn]');
[row,column]=size(Resistor)
while isreal(Resistor) && row==1 && column==2
end
fprintf('-------------------\n\n')

[Mehmed Saad]

Resistor=input('Enter values [R1...Rn]');

now in cmd what you are doing is directly entering two numbers like this

1 2

which will lead to

Error using Untitled4 (line 1)
Error: Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To
construct matrices, use brackets instead of parentheses.

if you enter

[1 2] 

i.e. put braces to make it an array no error will occur

a second way is to use string input but that'd be a bit complex

[Mariam Al Zarouni]

Another code was this: I get the same error here too. I also want to add another condition in the while loop which is the number of value must be even as i mentioned earlier but i didn't know where or how to put it. I know for even m(m,2)==0

close all;



Resistors=input(' Enter values of two resistances in ohm [R1 R2]= '); % to enter the values of the resistors

Total=length(Resistors);

[row,column]=size(Resistors);% matrix of the resistors

if isreal(Resistors) && row==1 && column>=2 % this is to make sure the values are real and the matrix is one row and infinite number of columns (values)

for number=1:Total

if Resistors(number)>0 % value of the resistor is positive or otherwise

equation=true;

else if Resistors(number)<=0

equation=false;

break;

end

end

end

end

if equation==false

disp(' invalid numbers .... please enter valid numbers')

end

end

disp ('===================================================================')

[Mariam Al Zarouni]

Okay Muhammad,I got my output. Can i just show you what my final output should look like?

[Mehmed Saad]

go ahead