How do I handle errors?

I am Trying the following sequence:

            kbinput = input( ' ' );
       if ischar(next)
           error('invalid string - ' );
           fprintf('....');

which expects a number

typing a character instead of a number I get this

Error using input Undefined function or variable 't'.

Error in dataplot (line 16)

[KSSV]

clc; clear all ;
kbinput = input( ' ' );
if ischar(kbinput)
    error('invalid string - ' );
    fprintf('....');
end

is the code? What you want to do actually?

Answer 1

[Guillaume]

By default, input interprets the user input as a matlab expression and evaluates it. If the user input is not a valid matlab expression then it returns an error.

If you want the user to be able to enter something that is not a matlab expression, then you need to pass the 's' option to input:

kbinput = input(' ', 's'); %and please use a prompt rather than an empty string

All input (including numbers) is then interpreted as text. If on the next line you meant to test that kbinput is char (instead of the undefined variable next), then the test will always return true. If you want to make sure that the input is truly a number:

kbinput = input(' ', 's');
numericvalue = str2double(kbinput);
if isnan(numericvalue)
    error('you did not enter a number');
end