How can I check if it is a string?

x = str2double(get(handles.demandValue,'String')); 
y = str2double(get(handles.generationValue,'String')); 
z = x - y; 

set(handles.generationBUS2,'String',num2str(z)); 

tf = isString(x)
 
if tf == 1
     f = errordlg('Dont write anything except number!','Error!');
     return
end

Hi,

I have created a small GUIDE project on my own and I want to check if the user input contains any words and stop the execution. I have tried to write the tf = isStringpart but the tf always returns 0. x and y variables are created on static text.

Thanks.

[Matt J]

Because x is the output of str2double(), you know it will always be a double, and therefore it will never be a string.

[Berkin Tan]

Thanks.

Answer 1

[Stephen23]

The simplest approach is to use ISNAN, because STR2DOUBLE will return NaN for any input that it cannot convert to numeric:

if isnan(x) || isnan(y)

[Berkin Tan]

Thanks for the answer.

Answer 2

[Image Analyst]

Try the lettersPattern() function:

pat = lettersPattern creates a pattern that matches text composed of one or more of letters. lettersPattern is Unicode tolerant.

or digitsPattern():

pat = digitsPattern creates a pattern that matches text composed of one or more digit characters. digitsPattern is Unicode tolerant.

Using those (there are other pattern functions by the way), you can determine whether the user entered letters, numerical digits, or a combination of them into the edit text box.