Short-circuit logic and dynamic structure referencing: Why does this not work?

1 次查看（过去 30 天）
Chris
Chris 2015-10-25
评论： Chris 2015-10-26
This behavior seems rather inconsistent, especially since by my understanding of short-circuit logic the A.(x) bit should not be evaluated if isfield(A,x) is false. Can someone help me understand this behavior? Thank you!
>> A = struct('apple',1, 'orange',1);
>> x = 'apple';
>> isfield(A,x) && A.(x)
ans =
1
>> x = 'banana';
>> isfield(A,x) && A.(x)
ans =
0
>> isfield(A,x) & A.(x)
Reference to non-existent field 'banana'.
>> for x = {'apple','banana'}
.. isfield(A,x) && A.(x)
.. end
Argument to dynamic structure reference must evaluate to a valid field name.

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2015-10-25
Nothing to do with short circuit logic.
for x = {'apple','banana'}
does not assign x = 'apple' and then x = 'banana': instead it assigns x = {'apple'} and then x = {'banana'}

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Simulink 的更多信息

标签

产品

Community Treasure Hunt

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

Start Hunting!

Translated by