~ operator in while not working as intended

I have this piece of code to make sure that the input is a whole number between 1 and 12

while (x~=1 || x~=2 || x~=3 || x~=4 || x~=5 || x~=6 || x~=7 || x~=8 || x~=9 || x~=10 || x~=11 || x~=12)
    fprintf("\nOption entered is not present in the menu. Please enter a valid number");
    x = input("\nEnter number corresponding to the conversion you want to perform: ");
end

However, the loop prints out the error message even the input is correct. Why is that so?

[Stephen23]

"Why is that so?"

Flawed logic. Can you name any value for which

x~=1 || x~=2

will return false?

[Sneha Chakravarthy]

Oh dear, it is quite obvious isn't it. Thanks for the help

Answer 1

[Mike]

In your code the or condition ( || ) ensures it always executes the error. You need to do a logical and i.e. change all || to &&.

Answer 2

[Steven Lord]

Let's take a simpler example.

check = @(x) (x ~= 1) | (x ~= 2)

check = function_handle with value:
    @(x)(x~=1)|(x~=2)

Does this return true for 1.5?

check(1.5)

ans = logical
   1

Does it return true for 3?

check(3)

ans = logical
   1

Does it return true for 1?

check(1)

ans = logical
   1

Whoops. Why? Well, 1 is equal to 1 so (x ~= 1) returns false. But 1 is not equal to 2 so (x ~= 2) returns true. And false or true returns true.

For something like this, you could use round (to make sure x is an integer value) and > and < to determine if it's in the bounds that you want. Alternately, if you want to limit x to being in a specific set of values use ismember.