Strange behavior when initializing empty cell in struct()

3 次查看（过去 30 天）
Chandler
Chandler 2024-6-20
评论： Stephen23 2024-6-20
Structs initialized with an empty cell using both {} and cell.empty within a struct() returns an empty struct object.
The following function reproduces that:
function print_hello_world()
obj = struct(MyProp=123, MyOtherProp={}); % or MyOtherProp=cell.empty
disp(obj)
disp(isempty(obj))
end
The obj variable is empty when running print_hello_world.
I have resorted to the following to go around this issue:
function print_hello_world()
obj = struct(MyProp=123);
obj.MyOtherProp = {};
disp(obj)
disp(isempty(obj))
end
The value of obj is as expected when running the above.
  1 个评论
Stephen23
Stephen23 2024-6-20
"Structs initialized with an empty cell using both {} and cell.empty within a struct() returns an empty struct object."
Exactly as documented here: https://www.mathworks.com/help/matlab/ref/struct.html#d126e1620618

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Aquatris
Aquatris 2024-6-20
编辑：Aquatris 2024-6-20
Ran in:
If you want to define the property as empty, then you should use '[]' instead of '{}'.
obj = struct(MyProp=123, MyOtherProp=[]);
disp(obj)
MyProp: 123 MyOtherProp: []
This is an intended behaviour. Here is the relevant part of the documentation:
s = struct(field1,value1,...,fieldN,valueN) creates a structure array with multiple fields.
  • ...
  • If any value input is an empty cell array, {}, then output s is an empty (0-by-0) structure. To specify an empty field and keep the values of the other fields, use [] as a value input instead.

类别

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

标签

产品


版本

R2022b

Community Treasure Hunt

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

Start Hunting!

Translated by