MATLAB Answers

Martin
0

conditional logic inside conditional logic

Asked by Martin
on 13 Jan 2019
Latest activity Commented on by Martin
on 13 Jan 2019
Accepted Answer by Jan
Hello, I would like to know if there is any way to write the following in one line ?
if isfield(hund.A)
if hund.A == 1
'do something'
end
end
Since I need to know if field 'A' exist I cannot just do if hund.A == 1 right away.
Is there a way to do something like this:
if isfield(hund.A) Then if hund.A == 1
'do something'
end
I would like to avoid too many if's. Thanks in advance...

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1 Answer

Answer by Jan
on 13 Jan 2019
Edited by Jan
on 13 Jan 2019
 Accepted Answer

if isfield(hund.A)
This will not work. I guess you mean:
if isfield(hund, 'A')
Then this works:
if isfield(hund, 'A') && hund.A == 1
The condition hund.A==1 is evaluated only, if the first condition is true. If the field 'A' does not exist, the 2nd part is not reached. This is called "shortcircuting".
Alternative: Create a function, which replies a default value for not existing fields:
function R = SafeGetField(S, F)
if isfield(S, F)
R = S.F;
else
R = [];
end
end
Then:
if isequal(SafeGetField(hund, 'A'), 1)
Or:
function T = CompareField(S, F, V)
if isfield(S, F)
T = isequal(S.F, V);
else
T = false;
end
end
and in the main code:
if CompareField(hund, 'A', 1)

  1 Comment

I meant as you said
if isfield(hund, 'A')
ya. Great, thanks for answer, didnt even knew that concept of "shortcircuting"

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