How to eval an expression without an error?

10 views (last 30 days)
Mr M.
Mr M. on 16 Oct 2018
Answered: Guillaume on 16 Oct 2018
I would like to eval an expression, for example eval('x=a+b;'); But in case of non-existing a or b, I dont want to get an error, just do nothing.

Answers (1)

Guillaume
Guillaume on 16 Oct 2018
Not withstanding that using eval is a really bad idea, if you do really want to do it and not stop on error, wrap it in a try statement.
try
eval('x=a+b');
end
I'd recommend you catch the error, to check that it is indeed due to a missing variable and not some syntax error in your eval:
try
eval('x=a+b');
catch mexc
if ~strcmp(mexc.identifier, 'MATLAB:UndefinedFunction') %the exception you get for undefined function or variable
rethrow(mexc); %not the error we expected, really error as something else happened
end
end

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!