Why does my it keep saying error on the input line?

This is my code

Exercise 2.6

clear;

clc;

%Get letter grade from user

grade = input('Enter your letter grade: ');

switch grade

case{A, a}

grade_letter = 'Excellent';

case{B, b}

grade_letter= 'Good';

case{C,c}

grade_letter= 'Ok';

case{D, d}

grade_letter= 'Below Average';

case{F, f}

grade_letter= 'Fail';

otherwise

grade_letter= 'Unknown';

end

disp(grade_letter)

and this is what im getting

Error in Ex2_6 (line 5)

grade = input('Enter your letter grade: ');

Answer 1

[Voss]

You should use the 's' option in input() to avoid interpreting the input, e.g., input A will be stored as the letter A rather than MATLAB looking for a variable called A.

grade = input('Enter your letter grade: ','s');

And you will also need quotes around the letters in all your case statements, e.g.:

switch grade
    case {'A','a'}
    % etc.

Or you could switch on upper(grade) or lower(grade) to only have to include one letter case in each case statement:

switch lower(grade)
    case 'a'
    % etc.

[Lesly]

hello, i tried it but its still giving me error

Error in Ex2_6 (line 5)

grade = input('Enter your letter grade: ','s');

[Voss]

Please copy and paste the entire error message (all the red text).

[Lesly]

Error using input

Unrecognized function or variable 'A'.

Error in Ex2_6(line 5)

grade = input('Enter your letter grade: ','s');

[Voss]

I get that same error when I don't use the 's' option and enter A, but I get no error when I use the 's' option. Strange.