MATLAB: Help with IF/Else statement in GUI

gui

Hi guys, i am new here. 🙂 I have a problem with IF/Else statement, but only in GUI. If i put only one if statement, like this
if s=='Add'
f=x+y;
end
It works, but when i add this:
if s=='Add'
f=x+y;
end
if s=='Substract'
f=x-y;
end
It doesn't work.Also, if i only use
if s=='Substract'
  f=x-y;
  end
it works.I don't have a clue why is this happening.Any idea?

Best Answer

There is not connection to the fact, that the code "runs in a GUI" - by the way: there is even nothing like "running in GUI". Code is code.
The problem is the comparison of a string the the == operator, which performs an elementwise comparison. If the compared strings have a different number of characters, such a comparison must fail.
Use strcmp instead:
if strcmp(s, 'Add')
  f = x+y;
end
if strcmp(s, 'Substract')
  f = x-y;
end
Or with switch/case:
switch s
  case 'Add'
     f = x+y;
  case 'Subtract'
     f = x-y;
  otherwise  % No SWITCH without OTHERWISE!
     error('Unexpected value of [s]');
end
Note: In your question you write "doesn't work". Please post the complete error message in the future, because these messages contain valuable information to solve the problem.
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