How do I ensure an input as a number and not a letter/set of letters?

I've tried a lot of methods for checking if my input x is a number or letter.

I understand that normally variables are set to double data types. So when I put in a letter or a word, understandably MATLAB freaks out and I get a sea of red.

This part of my program selects from one of 14 functions. If you input 1 when prompted, you get the first function, if you input 2, you get the second, etc.

I need to check to make sure that the user is only inputting a number from 1 to 14, and doing this involves checking if the user has put in random letters or something that isn't a number (e.g. "eihsgdf").

This is what I have:

xIsNumber = 0;
while xIsNumber == 0
        x = input("Write the number of the converter you want to open here: "); %User enters what number converter to open
    if isnumeric(x) == 0 || x ~= 1 || x ~= 2 || x ~= 3 || x ~= 4 || x ~= 5 || x ~= 6 || x ~= 7 || x ~= 8 || x ~= 9 || x ~= 10 || x ~= 11 || x ~= 12 || x ~= 13 || x ~= 14 %Make sure the input is only from 1 to 14
    disp("You have entered something wrong for your choice of converter. Please ensure you're typing ONLY a number from 1 to 14.") %User is notified that their input is wrong
        xIsNumber = 0; %Loops back to the x = input() above
    else
        xIsNumber = 1; %Escape the loop since the correct input has been made
    end
end

I know this can be simplified, but I'm just looking to see if the input 'x' is a number from 1 to 14.

I get this if i put in "gfd" for example:

Write the number of the converter you want to open here: gfd
Error using input
Unrecognized function or variable 'gfd'.

Error in script (line 35)
        x = input("Write the number of the converter you want
        to open here: "); %User enters what number converter to
        open

I know that putting letters in freaks the program out as mentioned above, so how do I avoid this? I tried making 'x' a string and going from there but the problem flipped and it didn't detect when I DID put a number from 1 to 14.

I'm very confused on what to do.

Answer 1

[Stephen23]

It is more robust to return a character vector from input:

p = 'Write the number of the converter you want to open here: ';
x = [];
while isempty(x)
    tmp = str2double(input(p,'s'));
    if ismember(tmp,1:14)
        x = tmp;
    else
        disp('try again')
    end
end

[Simon T]

That seemed to work. Cheers!

[Stephen23]

A compact version:

x = NaN;
while isnan(x)
    x = str2double(input('Enter an integer from 1 to 14: ','s'));
    x(~ismember(x,1:14)) = NaN;
end

[Daniel Prieto]

yeah what is " ismember" and "isnan", very unfamiliar with Matlab and none of that is making sence

Answer 2

[KSSV]

YOu can use isstring.

https://in.mathworks.com/help/matlab/ref/isstring.html

[Simon T]

I tried that, and the problem is in the x = input(...) line.

The program can't pass that line unless something is done before or during that line.

Answer 3

[madhan ravi]

second syntax

If numeric then str2double()

[Simon T]

I'll give this a try - how do I check the "if numeric" part?

[madhan ravi]

You already did isnumeric()