Hi, I am asking the user for input and the input should be either "AA" "Aa" or "aa". How can I validate the input using a while loop? I don't think my code works.Thanks!

parentOneA = input("Enter Parent 1's A Trait: ")
% Error checking input
while parentOneA ~= "AA" || parentOneA ~= "Aa" || parentOneA ~= "aa";
    parentOneA = input("Enter Parent 1's A Trait: ")
end

[Stephen23]

There is no string for which this will return false:

parentOneA ~= "AA" || parentOneA ~= "Aa" || parentOneA ~= "aa";

At least two equality operators will return true, so the output will always be true because you used OR:

true || false || true   ->   true

Rather than writing them out individually, a better approach is to simply use strcmpi:

while ~strcmpi(parentOneA,'AA')

[Sindar]

^ unless 'aA' is an invalid option

Answer 1

[Sindar]

You're requiring that it be all valid entries simultaneously

parentOneA = input("Enter Parent 1's A Trait: ")
% Error checking input
while parentOneA ~= "AA" && parentOneA ~= "Aa" && parentOneA ~= "aa";
    parentOneA = input("Enter Parent 1's A Trait: ")
end

or

valid_inputs = {'AA';'Aa';'aa'};
parentOneA = input("Enter Parent 1's A Trait: ")
while ~any(strcmp(parentOneA,valid_inputs))
    parentOneA = input("Enter Parent 1's A Trait: ")
end

[Walter Roberson]

while ~ismember(parentOneA, ["AA", "Aa", "aa"])