Check input is a string or Char if so reprompt

I am struggling to fidn a way to check a input if its any type of string or char and if so reprompt the user.

Code is below:

a = input("Please enter a number: "); %Takes user input for number that is to be converted
while isempty(a)
    disp('Invalid input please enter a number!')
    a = input("Please enter a number: ");
end
convtype = input("Please enter the conversion type: "); %Takes user input for the cnversion type that they want
while isempty(convtype)|| convtype < 1 || convtype > 14
    disp('Invalid conversion type selection please make a selection between 1 and 14!')
    convtype = input("Please enter the conversion type: ");
end

[Stephen23]

If you specify the 's' option then INPUT will always return a character vector:

txt = input(prompt,'s')

[Methat]

so it will return that value as a charecter lets say I need to use that value later for a calculation I would need to convert it back to a numerical input. Also if I were to do this would I use ischar() to check if its charecter to ten reprompt the user to re-enter their value?

Answer 1

[Walter Roberson]

a = input("Please enter a number: "); %Takes user input for number that is to be converted
while ~isnumeric(a) || numel(a) ~= 1
    disp('Invalid input please enter a number!')
    a = input("Please enter a number: ");
end
convtype = input("Please enter the conversion type, integer 1 to 14: "); %Takes user input for the cnversion type that they want
while ~isnumeric(convtype) || numel(convtype) ~= 1 || convtype ~= floor(convtype) || convtype < 1 || convtype > 14
    disp('Invalid conversion type selection please make a selection between 1 and 14!')
    convtype = input("Please enter the conversion type as an integer 1 to 14: ");
end

[Methat]

Hi I was just wondering what does the ~ do specifically as I have never seen the use of ~ in MATLAB. Sorry for this question if it is obvious I am very new to MATLAB.

[Dyuman Joshi]

~ is the logical not operator - not, ~

~= is ne, ~=

See more here - https://in.mathworks.com/help/matlab/matlab_prog/matlab-operators-and-special-characters.html

https://in.mathworks.com/help/matlab/logical-operations.html?s_tid=CRUX_lftnav

[Methat]

Oh I see thanks for the help I will try using ~ in my current iteration on the code thanks for linking those explinations.