MATLAB: How to repeat question until valid input is entered

repeatwhile

I have a bit of code that asks two questions. I want the questions to continue to be prompted until a valid response is given. For the first question, they need to enter in any number greater than zero. For the second question they must enter in A, B, C, D, or E. Any other response should either repeat the question or potentially rephrase the question to emphasize the correct format. Here is the code that works as long as they enter the response correctly.
%Input
fpc = input('Enter specified compressive strength (psi): ');
Facility = input('Chooose facility letter in upper-case (A-E): ', 's');
And just to show one of the things I've tried:
while Facility ~= 'A,B,C,D,E';
Facility = input('Chooose facility letter in upper-case (A-E): ', 's');
end
And this actually does work, unless the user enters in a value that is more than one character long, then I get a 'matrix dimensions must agree', which doesn't make sense to me. In any case, I'm sure there is a better way to do this.
Thank you

Best Answer

What if you implement it using a while loop?
%Input
clc;
clear all;
close all;
fpc = input('Enter specified compressive strength (psi): ');
coffee = 0;
while ~coffee
Facility = input('Chooose facility letter in upper-case (A-E): ', 's');
if ~ismember(Facility, {'A','B','C','D','E'})
        coffee = 0;
else coffee = 1;
end
end
This will guarantee that the Facility will take a character from A-E, and if not, will continue to loop.
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