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Custom warning message does not show when called within a function

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Pascal Weller
Pascal Weller on 4 Nov 2020
Commented: Mario Malic on 4 Nov 2020
Hello,
I have got difficulties to get custom warning messages to pop up in MATLAB's console.
Scenario:
I start execution of the main script. At some point it calls a function that is coded in a seperate .m file. From this called function I would like to display a warning. It executes the line where the warning is called but nothing shows up in the console. How do I make this warning to show up? Thanks in advance for your help!
Dummy code:
Main script which is run:
clear;
fd = 'test.h5'
...
foo(fd);
...
Script for function foo():
function foo(fd)
if exist(fd,'file')
warning('''%s'' already exists. Overwriting it.',fd);
...
end
...
end
Btw: When I put a fprintf() or disp() or error() instead of the warning() it will show up in the console.
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Accepted Answer

Luna
Luna on 4 Nov 2020
Edited: Luna on 4 Nov 2020
I agree with Walter, put that code on command window to get all warnings on:
warning all on;
Be sure that your if statement result is true. I recommend you to try this first:
function foo(fd)
if exist(fd,'file') == 2 % this is about exist function outputs. Check all the output states. if it is 2, that means file exists.
warning('''%s'' already exists. Overwriting it.',fd);
else
warning([fd, ' file does not exist.']);
end
end
Here is the link for exist function documentation:
  1 Comment
Mario Malic
Mario Malic on 4 Nov 2020
It looks like that if expression is true when expression result is nonempty and contains only nonzero elements (logical or real numeric). Otherwise, the expression is false.

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