Instead of outputting error how to display warning?

I have a GUI where users are typing values into a table. In order for the calculations to work they have to type in numbers and not letters. This way i can convert the numbers using str2num.

Is there a way to check if str2num will work, and if it doen't then I can display a msgbox telling the users to only type in numbers?

[Stephen23]

Using the right tools makes this much easier:

1. Use STR2DOUBLE (instead of STR2NUM) which returns NaN if the input is not a string of a valid number.
2. If the output is NaN display the message box.

Avoid STR2NUM (it uses evil EVAL, which is best avoided)

[Yazan]

You may check if the user enters a number as follws:

x = input('Insert a number\n', 's');
if isnan(str2double(x))
    error('Enter a number without letters');
end

[Dc215905]

Thank you!

Answer 1

[Animesh]

Hello,

According to my understanding you want to display a custom message when the user inputs wrong data format.

We can display a custom error message with the help of error function.

Sample Code: -

x = input("Input number\n",'s') %Input from the user
if isempty(str2num(x))
    error("The input is not of correct format.\n")
end

For further reference on error use: - https://www.mathworks.com/help/matlab/ref/error.html

For further reference on str2num use: - https://www.mathworks.com/help/matlab/ref/str2num.html