MATLAB函数可重新分配未定义数量的变量的值

Question

I want to write a MATLAB function that can take an undefined number of variables, change their values, and output them under the same names. I got part way there if I don't mind listing the variables twice:

function [varargout]=testing(varargin)
    for i=1:nargin
        varargout{i}=varargin{i}*2;
    end
end

and

x=5;
y=3;
z=6;
[x,y,z]=testing(x,y,z);

But I don't want to list the variable names twice. Is there anyway I can call the function like this instead?

testing(x,y,z);

I tried using inputname, but I couldn't figure out how to make it work.

Answer 1

Blindly adjusting values across workspaces is highly unadvisable and can lead to hard to detect bugs and make the code difficult to maintain. Arguments against this essentially mirror arguments against global variables . It will be far more reliable to explicitly control the data you want to manipulate. Yes, this will probably require you to store your data differently.

For example, you can use a structure :

function testcode()
mydata.a = 1;
mydata.b = 2;
mydata.c = 3;
mydata.d = 4;

mydata = multiplydata(mydata, 2);
disp(mydata)
end

function [datastruct] = multiplydata(datastruct, n)
varnames = fieldnames(datastruct);
for ii = 1:length(varnames)
    datastruct.(varnames{ii}) = datastruct.(varnames{ii})*n;
end
end

Which outputs:

>> testcode
    a: 2
    b: 4
    c: 6
    d: 8

This isn't really any functionally different than using varargin / varargout , but if you write your code in such a way that you're utilizing structures from the beginning, you don't have to deal with the extra unpacking step (eg x = varargin{1} , etc.).

---

If, for whatever reason, you absolutely must blindly adjust your variables (which, again, please don't), then you can use assignin :

function testcode()
a = 1;
b = 2;
c = 3;
d = 4;

multiplydata(2, a, b, c, d);
fprintf('a: %u\nb: %u\nc: %u\nd: %u\n', a, b, c, d)
end

function multiplydata(n, varargin)
for ii = 1:length(varargin)
    varname = inputname(ii + 1);
    assignin('caller', varname, varargin{ii}*n)
end
end

Which returns:

>> testcode
a: 2
b: 4
c: 6
d: 8